This study was focused to assess major and trace elements in bauxitic duricrusts from Ngaoundal and its surroundings in order to establish their mining interest. To this end, fieldworks, mineralogical and geochemical ...This study was focused to assess major and trace elements in bauxitic duricrusts from Ngaoundal and its surroundings in order to establish their mining interest. To this end, fieldworks, mineralogical and geochemical analyses were carried out. Four facies of duricrust were identified and characterized from the summit to the top of the slope of the Ngaoundal mountain: scoriaceous, pisolitic, nodular and massive. Mineralogical and geochemical analyses performed on 16 samples, revealed a significant concentration of Al<sub>2</sub>O<sub>3</sub> mainly in the scoriaceous facies (over 45% in grade), moderate in Fe<sub>2</sub>O<sub>3</sub> (averaging 23.69%) and SiO<sub>2</sub> (averaging 21.7%). Trace elements were generally low, excluding Cr (421 ppm on average), Zr (327 ppm on average and V (213 ppm on average). In addition, the limited quantities of alkalis (Na<sub>2</sub>O, K<sub>2</sub>O) and alkaline earths metals (MgO, CaO) coupled with the very high values of Chemical Index of Alteration (CIA) and Mineralogical Index of Alteration (MIA), (more than 99%) attest to the intense weathering of the studied materials. Allitization and monosiallitization constituted the crystallochemical phenomena that have led to the development of bauxitic minerals. More than 90% of gibbsite in scoriaceous facies, 52.21% - 76.01% of kaolinite in pisolitic facies and more than 40% of hematite in nodular facies were quantified. The relationships between the constitutive components indicated their interdependency during the bauxitization phenomenon. The mineralogical and geochemical properties highlighted the mining interest of the studied duricrusts to be valorized.展开更多
A new manufactured soil product (Turba) was produced using acidified bauxite residue into which 10% green waste compost had been incorporated. A laboratory/greenhouse experiment was carried out to determine if sand co...A new manufactured soil product (Turba) was produced using acidified bauxite residue into which 10% green waste compost had been incorporated. A laboratory/greenhouse experiment was carried out to determine if sand could be used as an ingredient or an amendment for Turba. Sand was added at rates of 0%, 5%, 10%, 25, 50% and 75% (w/w) in two different ways 1) by incorporating it into the Turba during its manufacture (IN) or 2) by mixing it with Turba aggregates after their manufacture (OUT). Incorporation of sand into Turba aggregates (IN) decreased the percentage of sample present as large aggregates (2 - 4 mm dia.) after crushing and sieving (<4 mm) and also reduced the stability of 2 - 4 mm dia. formed aggregates (to dry/wet sieving) and are therefore not recommended. In a 16-week greenhouse study, ryegrass shoot yields were greater in Turba than in sand [and decreased with increasing sand additions (OUT)] while root dry matter showed the opposite trend. The greater grass growth in Turba than sand was attributed to incipit water stress in plants grown in sand and this may have promoted greater allocation of assimilates to roots resulting in a greater root-to-top mass ratio. The much lower macroporosity in Turba coupled with the solid cemented nature of Turba aggregates resulted in production of thinner roots and therefore greater root length than in sand. Turba (manufactured from bauxite residue and compost added at 10% w/w) is a suitable medium for plant growth and there is no advantage in incorporating sand into, or with, the Turba aggregates.展开更多
As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-s...As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.展开更多
To accurately identify the factors affecting the formation of stable aggregates in bauxite residue during the soil formation process,the comprehensive effects of a combined chemical-biological amelioration strategy in...To accurately identify the factors affecting the formation of stable aggregates in bauxite residue during the soil formation process,the comprehensive effects of a combined chemical-biological amelioration strategy including solid wastes and a functional microorganism on aggregate size distribution and its stability in bauxite residue were investigated during a 365-d simulation experiment.The results showed that the combined amelioration effectively reduced the saline alkalinity of bauxite residue,and markedly changed the contents of aggregate-associated chemical binding agents.Desulfurization gypsum and maize straw-Penicillium oxalicum(P.oxalicum)differentiated the formation of aggregates within different sizes.Maize straw-P.oxalicum stimulated the formation of water-stable macroaggregates with more durable erosion resistance by the wet-sieving and laser dynamic diffraction analysis.The Pearson correlation analysis showed that exchangeable polyvalent metal ions,pyrophosphate extractable Fe oxide,and organic carbon exhibited positive correlations with aggregate stability during the 365-d incubation.The findings in this study may provide data support and engineering practical reference for ecological restoration in the disposal areas.展开更多
Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with...Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.展开更多
Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentration...Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentrations of moss crusts,and soil contamination indices in Wachangping bauxite tailing areas in Guizhou Province,China were measured and analyzed.In a total of 40 species belonging to 19 genera and 12 families of moss in the study areas,Ditrichum flexicaule(Schwaegr.)Hamp.(DF),Oxystegus cylindricus(Brid.)Hilp.(OC),and Ditrichum brevidens Nog.(DB)are the dominant moss crusts.Moss species diversity in different habitats has a certain regularity:waste residues area<waste rocks area<ore stockpile area<slope shrub area<shrub area by gutter<slope shrub herbaceous area.Sorenson diversity index(β)of moss species is influenced by microenvironment and substrate.Concentrations of Al,Mg,Ca,Fe,K,and Ti are the largest in DB(2,990 to 73,210 mg kg^(-1)),followed by those in DF(2,900 to 61,890 mg kg^(-1)),and are the smallest in OC(690 to 32,240 mg kg^(-1)),which show that the three moss crusts have different bioaccumulation capacities.Metal contents in underlying soils of moss crusts are higher than the background levels.Bioaccumulation factor(BAF)of Al,Mg,Ca,Fe,and K in three moss crusts are decreased in the following order:DB>DF>OC.Single factor pollution index(Ps)and Nemero comprehensive pollution index(Pc)of six metal are much greater than 3,and the index of geoaccumulation(Igeo)(1geo<5)reveals that the soil environment is at moderately to seriously contaminated levels.Principal components analysis(PCA)shows that there is no significant correlation between p H value,and metal contents(Al,Mg,Fe,K and Ti),soil temperature(ST)and metal contents(Al,Mg,Fe,K and Ti).Soil humidity(SH)is negatively correlated with metal contents(Al,Mg,Fe,K and Ti).These three environmental factors have little effect on the distribution of metal.Result also reflects that DB moss is readily able to both tolerate and accumulate metal,which makes it a suitable bioindicator of multiple metal contamination in Wachangping bauxite tailing areas.展开更多
Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water conten...Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water content and mud water separation rate was established to achieve efficient resource utilization,and the feasibility of foam lightweight soil(FLS)prepared from BT was investigated.The effects of industrial waste residues(fly ash and slag powder)on the properties of FLS were studied.Meanwhile,the micro-mechanisms were revealed by XRD,SEM-EDS,and TG-DSC.The results revealed that fly ash reduced the workability and compressive strength of FLS.Slag powder can significantly enhance the compressive strength of FLS,which increased by 18.60%-23.26%,17.07%-58.54% and 12.12%-52.12%,respectively.Besides,slag powder can improve the long-term water stability performance and enhance carbonation resistance.XRD and thermal analyses showed that adding fly ash decreased the hydration degree of FLS,leading to a decrease in the hydration products.Slag powder improved the pore structure and compacted the skeleton structure of FLS.This study would provide an effective way to realize the resource utilization of BT,fly ash,and slag powder,with certain socio-economic and environmental benefits.展开更多
Recovery of microbial functions is one of the critical processes in the nutrient cycling of bauxite residue for improving revegetation.Straw is considered to be effective to increase microbial diversity and drive the ...Recovery of microbial functions is one of the critical processes in the nutrient cycling of bauxite residue for improving revegetation.Straw is considered to be effective to increase microbial diversity and drive the development of the microbial community,but its effect on microbial carbon metabolism has not been illustrated.The present study evaluated the effects of phosphogypsum(PG),straw(SF)and phosphogypsum plus straw(PGSF)on physicochemical properties,enzyme activities,and microbial carbon metabolism activities in bauxite residue.After 180 days incubation,PG,SF and PGSF treatment significantly reduced the residue pH from 10.85 to 8.64,9.39 and 8.06,respectively.Compared to CK treatment,SF treatment significantly increased the content of total organic carbon(TOC)and organic carbon fractions(DOC,MBC,EOC,and POC).In addition,straw addition significantly increased glucosidase,cellulose,urease,and alkaline phosphatase by 7.2-9.1 times,5.8-7.1 times,11.1-12.5 times,and 1.1-2.2 times,respectively.The Biolog results showed that straw addition significantly increased microbial metabolic activity(AWCD)and diversity in bauxite residue.Redundancy analysis indicated total nitrogen(TN)and carbon fractions(POC,MBC and DOC)were the most important environmental factors affecting microbial metabolic activity and diversity in bauxite residue.These findings provided us with a biogeochemical perspective to reveal soil formation in bauxite residue and suggested that nutrient supplement and regulation of salinity-alkalinity benefit the establishment of microbial communities and functions in bauxite residue.展开更多
The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and micr...The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and microtopography.The results showed a significant decrease in Na_(2)O content(>30 wt.%)of FGD gypsum-treated bauxite residue after 30 min of mechanical ball milling.Mechanical ball milling resulted in differentiation of the elemental distribution,modification of the minerals in crystalline structure,and promotion in the dissolution of alkaline minerals,thus enhancing the acid neutralization capacity of bauxite residue.5 wt.%FGD gypsum combined with 30 min mechanical ball milling was optimal for the dealkalization of bauxite residue.展开更多
Through core observation,thin section identification,X-ray diffraction analysis,scanning electron microscopy,and low-temperature nitrogen adsorption and isothermal adsorption experiments,the lithology and pore charact...Through core observation,thin section identification,X-ray diffraction analysis,scanning electron microscopy,and low-temperature nitrogen adsorption and isothermal adsorption experiments,the lithology and pore characteristics of the Upper Carboniferous bauxite series in eastern Ordos Basin were analyzed to reveal the formation and evolution process of the bauxite reservoirs.A petrological nomenclature and classification scheme for bauxitic rocks based on three units(aluminum hydroxides,iron minerals and clay minerals)is proposed.It is found that bauxitic mudstone is in the form of dense massive and clastic structures,while the(clayey)bauxite is of dense massive,pisolite,oolite,porous soil and clastic structures.Both bauxitic mudstone and bauxite reservoirs develop dissolution pores,intercrystalline pores,and microfractures as the dominant gas storage space,with the porosity less than 10% and mesopores in dominance.The bauxite series in the North China Craton can be divided into five sections,i.e.,ferrilite(Shanxi-style iron ore,section A),bauxitic mudstone(section B),bauxite(section C),bauxite mudstone(debris-containing,section D)and dark mudstone-coal section(section E).The burrow/funnel filling,lenticular,layered/massive bauxite deposits occur separately in the karst platforms,gentle slopes and low-lying areas.The karst platforms and gentle slopes are conducive to surface water leaching,with strong karstification,well-developed pores,large reservoir thickness and good physical properties,but poor strata continuity.The low-lying areas have poor physical properties but relatively continuous and stable reservoirs.The gas enrichment in bauxites is jointly controlled by source rock,reservoir rock and fractures.This recognition provides geological basis for the exploration and development of natural gas in the Upper Carboniferous in the study area and similar bauxite systems.展开更多
A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was developed.The combination of recycled FeCl_(3)solution and E...A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was developed.The combination of recycled FeCl_(3)solution and EDTA activated desulfurization gypsum lowered the bauxite residue pH to 7.20.Moreover,it also improved the residual Ca state,with its contribution to the total exchangeable cations increased(68%-92%).Notably,the slow release of exchangeable Ca introduced through modified desulfurization gypsum induced a phase transition of the alkaline minerals.This treatment stabilized the dealkalization effect of bauxite residue via reducing its overall acid neutralization capacity in abating pH rebound.Hence,this approach can provide guidance for effectively utilizing desulfurization gypsum to achieve stable regulation of alkalinity in bauxite residue.展开更多
The low thermal conductivity and light mass of castables for tundish permanent linings are crucial for minimizing the heat loss of molten steel.In consideration of the low bulk density and thermal conductivity of pear...The low thermal conductivity and light mass of castables for tundish permanent linings are crucial for minimizing the heat loss of molten steel.In consideration of the low bulk density and thermal conductivity of pearlescent sand,the thermal insulation performance of castables was attempted to be improved by adding pearlescent sand.Pearlescent sand was modified to prevent the strength of its porous structure from deteriorating.The modification mechanism of pearlescent sand and the effect of pearlescent sand on the performance of bauxite castables were studied.The results suggested that the addition of the modified pearlescent sand significantly raised the apparent porosity and decreased the bulk density of bauxite castable.At 1000℃,the bulk density of more than 60%of the modified pearlescent sand-bauxite castable was only 2.03 g/cm^(3).The mechanical properties and thermal shock resistance of the modified pearlescent sand-bauxite castable were inferior to those of conventional bauxite castable but were adequate to meet the use conditions of casta-bles for tundish permanent linings.At high temperatures of 200-800℃,the thermal conductivity of more than 60%of the modified pearlescent sand-bauxite castable was smaller than that of conventional bauxite castable.The addition of the modified pearlescent sand can greatly reduce the thermal conductivity and bulk density of bauxite castable.展开更多
Since their discovery, zeolites have generated significant interest in various technological fields, such as molecular sieves, ion exchangers, catalysts, and especially as adsorbents. This article focuses on character...Since their discovery, zeolites have generated significant interest in various technological fields, such as molecular sieves, ion exchangers, catalysts, and especially as adsorbents. This article focuses on characterizing the types of zeolites present in Sangarédi bauxite. To achieve this objective, we conducted a physico-chemical characterization (moisture, particle size, volumetric density, porosity) and determined the optimal conditions for activating the zeolite samples (15% H2SO4 concentration, L/S ratio of 2, temperature of 70˚C, duration of 3 hours). Techniques used to characterize the samples included desiccation gravimetry, mechanical sieving, X-ray fluorescence (atomic percentage), X-ray diffraction, BET method, and water pycnometry. Additionally, we assessed the adsorption capacity of zeolites activated by the elimination of methylene blue in an aqueous solution, which was selected as a model water pollutant. According to X-ray fluorescence and diffraction data, there are nine types of zeolite in Sangarédi bauxite, divided into five families. Regarding physical activation, a good porous structure was observed at a temperature of 300˚C to 340˚C for 4 hours. Above this range, material condensation occurs, leading to a sudden increase in mass loss, which can be explained by a change in their crystalline structure. After treatment with sulfuric acid, the activated samples showed an increase in specific surface area (from 72 to 130.25 m2∙g−1 on average) and porosity (from 0.07% to 0.3%), as well as an increased susceptibility to methylene blue discoloration (from 13.58% to 30.35%). These results confirm the improvement in the microporous structure and the formation of a more developed molecular sieve network. Thanks to the identified structural and textural characteristics, it can be concluded that the activated zeolites obtained are extremely reactive materials and can be used effectively in water treatment.展开更多
The Sangarédi bauxite deposit in the Republic of Guinea contains several bauxite types depending on their litho-genetics. For rational and sustainable exploitation, determining the physical and mechanical propert...The Sangarédi bauxite deposit in the Republic of Guinea contains several bauxite types depending on their litho-genetics. For rational and sustainable exploitation, determining the physical and mechanical properties of these different bauxite types is essential for mining companies. This paper presents a model for the physico-mechanical characterization of Sangarédi bauxites according to their litho-genetic type. Eight pits were drilled, and samples were collected from different layers at different depth intervals for each bauxite type. Physical and mechanical characterization tests were then carried out on 27 samples to determine the following parameters: water of absorption (%), compressive strength (kgf/cm2) and dynamic tensile strength (kgf/cm2). The effect of depth of sampling on these physico-mechanical parameters was evaluated. An average value of the parameters was made for each bauxite type. The results showed that the physico-mechanical characteristics of bauxites depend on the depth of sample collection, and the average value of the parameters constitutes the representative values of the bauxite type. Finally, a comparative study of the average value of the physico-mechanical parameters of the different bauxite types was carried out.展开更多
The demand for useful ores has been growing steadily, especially since there is increasing interest in bauxite ores. This growing demand is prompting researchers to justify a large number of research projects on bauxi...The demand for useful ores has been growing steadily, especially since there is increasing interest in bauxite ores. This growing demand is prompting researchers to justify a large number of research projects on bauxites. The aim of this work is to characterize the Boundou-Waadé bauxite deposit. The proposed methodology is mainly based on sample collection, stratigraphic logs, cross-sections and geological maps. Samples were analyzed at the Compagnie des Bauxites de Guinée laboratory. Geochemical data were processed using statistical methods. Devonian sedimentary formations and Mesozoic dolerites characterize the study area. The Boundou-Waadé bauxite deposit was developed on Devonian and Mesozoic formations. Stratigraphic logs show the succession of formations, with the bedrock overlain by the alteration crust. The bauxitic zone, the transition zone and the ferruginous laterites are the subject of petrographic studies, with both zones (bauxitic and transition) containing some ferriplantite. Mineralogical analysis clearly shows that gibbsite, goethite, alumogoethite, rutile and clay minerals are present. The geochemical study of the major elements shows that as SiO2 and Fe2O3 content decreases, Al2O3 content increases and TiO2 and Al2O3 content increases in the same direction.展开更多
The chemical and mineralogical composition of bauxite deposits is a key factor in the profitability of refining processes. The study of bauxites from the Saföfö site has assessed variations in chemical and m...The chemical and mineralogical composition of bauxite deposits is a key factor in the profitability of refining processes. The study of bauxites from the Saföfö site has assessed variations in chemical and mineralogical composition under various conditions, as well as the optimum conditions for their exploitation. The methodologies used in this study include experimental methods for determining moisture content, chemical composition, mineralogical composition, and specific density of bauxite. The results show significant variation in moisture content among the bauxite samples, with values ranging from 2.90% to 17.80%. The silica percentages in the samples range from 1.69% to 8.14%, while alumina percentages vary from 36.81% to 54.03%. After calcination, alumina oxide percentages range from 40% to 75%. After chemical activation, alumina oxides Al2O3 range from 40% to over 50%. Gibbsite is the most abundant mineral, accounting for about 60% - 70% of the total composition of the bauxite samples. Samples A to F have bulk densities varying between approximately 3.6 and 3.9. Sample B has the highest density, around 3.9, while sample C has the lowest, at around 3.5. Bauxite mining at the Saföfö site offers significant potential for the alumina industry, provided appropriate processing methods are selected to maximize quality and profitability while minimizing environmental impact.展开更多
Reaction behaviors of sulfur and iron compounds in sodium aluminate solutions were investigated. The results show that iron compounds can remarkably remove the S2 but cannot get rid of S2Oc2-, SO^2- and SO4^-2 in sodi...Reaction behaviors of sulfur and iron compounds in sodium aluminate solutions were investigated. The results show that iron compounds can remarkably remove the S2 but cannot get rid of S2Oc2-, SO^2- and SO4^-2 in sodium aluminate solutions. The removal efficiency of S^2- using ferrous compound and ferric compound can reach 86.10% and 92.70% respectively when the iron compounds were added with a molar ratio of 2：1 compared with the sulfur in liquors at 100℃. Moreover, several same compounds are formed in those two desulfurization processes with ferrous or ferric compounds, including erdite, hematite, amorphous ferrous sulfide, polymerized sulfur-iron compounds and ferric sulfate. The major difference between these two processes is that the erdite generated from ferrous compounds at the initial reaction stage will convert to a sodium-free product FeS2 at the subsequent stage.展开更多
The flotation of diaspore and three kinds of silicate minerals, including kaolinite, illite and pyrophyllite, using an organosilicon cationic surfactant (TAS101) as collector and starch as depressant was investigated....The flotation of diaspore and three kinds of silicate minerals, including kaolinite, illite and pyrophyllite, using an organosilicon cationic surfactant (TAS101) as collector and starch as depressant was investigated. The results show that both diaspore and aluminosilicate minerals float readily with organosilicon cationic collector TAS101 at pH values of 4 to 10. Starch has a strong depression effect for diaspore in the alkaline pH region but has little influence on the flotation of aluminosilicate minerals. It is possible to separate diaspore from aluminosilicate minerals using the organosilicon cationic collector and starch depressant. Further studies of bauxite ore flotation were also conducted, and the reverse flotation separation process was adopted. The concentrates with the mass ratio of Al2O3 to SiO2 of 9.58 and Al2O3 recovery of 83.34% are obtained from natural bauxite ore with the mass ratio of Al2O3 to SiO2 of 6.1 at pH value of 11 using the organosilicon cationic collector and starch depressant.展开更多
For the low-grade gibbsitic bauxite,the leaching rate of alumina is very low during the Bayer process.The acid leaching method is attracting more attention,and the hydrochloric acid leaching was developed rapidly.The ...For the low-grade gibbsitic bauxite,the leaching rate of alumina is very low during the Bayer process.The acid leaching method is attracting more attention,and the hydrochloric acid leaching was developed rapidly.The mineral composition and chemical composition were investigated by X-ray diffraction analysis and semi-quantitative analysis.The thermodynamics of leaching process was analyzed.The results show that the major minerals in the bauxite are gibbsite,secondly goethite and quartz,anatase and so on.The acid leaching reactions of the bauxite would be thermodynamically easy and completed.Under the conditions that ore granularity is less than-55 μm,the L/S ratio is 100：7,and the leaching temperature is 373-383 K,the leaching time is 120 min and the concentration of HCl is 10%,both the leaching rates of Al and Fe are over 95%.The main composition of leaching slag is SiO2 which is easy for comprehensive utilization.展开更多
The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The resu...The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.展开更多
文摘This study was focused to assess major and trace elements in bauxitic duricrusts from Ngaoundal and its surroundings in order to establish their mining interest. To this end, fieldworks, mineralogical and geochemical analyses were carried out. Four facies of duricrust were identified and characterized from the summit to the top of the slope of the Ngaoundal mountain: scoriaceous, pisolitic, nodular and massive. Mineralogical and geochemical analyses performed on 16 samples, revealed a significant concentration of Al<sub>2</sub>O<sub>3</sub> mainly in the scoriaceous facies (over 45% in grade), moderate in Fe<sub>2</sub>O<sub>3</sub> (averaging 23.69%) and SiO<sub>2</sub> (averaging 21.7%). Trace elements were generally low, excluding Cr (421 ppm on average), Zr (327 ppm on average and V (213 ppm on average). In addition, the limited quantities of alkalis (Na<sub>2</sub>O, K<sub>2</sub>O) and alkaline earths metals (MgO, CaO) coupled with the very high values of Chemical Index of Alteration (CIA) and Mineralogical Index of Alteration (MIA), (more than 99%) attest to the intense weathering of the studied materials. Allitization and monosiallitization constituted the crystallochemical phenomena that have led to the development of bauxitic minerals. More than 90% of gibbsite in scoriaceous facies, 52.21% - 76.01% of kaolinite in pisolitic facies and more than 40% of hematite in nodular facies were quantified. The relationships between the constitutive components indicated their interdependency during the bauxitization phenomenon. The mineralogical and geochemical properties highlighted the mining interest of the studied duricrusts to be valorized.
文摘A new manufactured soil product (Turba) was produced using acidified bauxite residue into which 10% green waste compost had been incorporated. A laboratory/greenhouse experiment was carried out to determine if sand could be used as an ingredient or an amendment for Turba. Sand was added at rates of 0%, 5%, 10%, 25, 50% and 75% (w/w) in two different ways 1) by incorporating it into the Turba during its manufacture (IN) or 2) by mixing it with Turba aggregates after their manufacture (OUT). Incorporation of sand into Turba aggregates (IN) decreased the percentage of sample present as large aggregates (2 - 4 mm dia.) after crushing and sieving (<4 mm) and also reduced the stability of 2 - 4 mm dia. formed aggregates (to dry/wet sieving) and are therefore not recommended. In a 16-week greenhouse study, ryegrass shoot yields were greater in Turba than in sand [and decreased with increasing sand additions (OUT)] while root dry matter showed the opposite trend. The greater grass growth in Turba than sand was attributed to incipit water stress in plants grown in sand and this may have promoted greater allocation of assimilates to roots resulting in a greater root-to-top mass ratio. The much lower macroporosity in Turba coupled with the solid cemented nature of Turba aggregates resulted in production of thinner roots and therefore greater root length than in sand. Turba (manufactured from bauxite residue and compost added at 10% w/w) is a suitable medium for plant growth and there is no advantage in incorporating sand into, or with, the Turba aggregates.
基金supported by the National Key Research and Development Program of China(2022YFC2904400)Guangxi Science and Technology Major Project(Gui Ke AA23023033)。
文摘As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.
基金Projects(42177391,42477437)supported by the National Natural Science Foundation of ChinaProject(2024RC3041)supported by the Science and Technology Innovation Program of Hunan Province,China+1 种基金Project(2023CXQD064)supported by the Innovation-Driven Research Programme of Central South University,ChinaProject(242102321124)supported by the Henan Provincal Science and Technology Research Project,China。
文摘To accurately identify the factors affecting the formation of stable aggregates in bauxite residue during the soil formation process,the comprehensive effects of a combined chemical-biological amelioration strategy including solid wastes and a functional microorganism on aggregate size distribution and its stability in bauxite residue were investigated during a 365-d simulation experiment.The results showed that the combined amelioration effectively reduced the saline alkalinity of bauxite residue,and markedly changed the contents of aggregate-associated chemical binding agents.Desulfurization gypsum and maize straw-Penicillium oxalicum(P.oxalicum)differentiated the formation of aggregates within different sizes.Maize straw-P.oxalicum stimulated the formation of water-stable macroaggregates with more durable erosion resistance by the wet-sieving and laser dynamic diffraction analysis.The Pearson correlation analysis showed that exchangeable polyvalent metal ions,pyrophosphate extractable Fe oxide,and organic carbon exhibited positive correlations with aggregate stability during the 365-d incubation.The findings in this study may provide data support and engineering practical reference for ecological restoration in the disposal areas.
基金financially supported by the National Natural Science Foundation of China (No. 52062029)the Key Science and Technology Project of Gansu Province (No. 18YF1GA064)the Natural Science Foundation of Gansu Provence (No. 25JRRA094)。
文摘Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.
基金the National Natural Science Foundation of China(NSFC No.32360309)。
文摘Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentrations of moss crusts,and soil contamination indices in Wachangping bauxite tailing areas in Guizhou Province,China were measured and analyzed.In a total of 40 species belonging to 19 genera and 12 families of moss in the study areas,Ditrichum flexicaule(Schwaegr.)Hamp.(DF),Oxystegus cylindricus(Brid.)Hilp.(OC),and Ditrichum brevidens Nog.(DB)are the dominant moss crusts.Moss species diversity in different habitats has a certain regularity:waste residues area<waste rocks area<ore stockpile area<slope shrub area<shrub area by gutter<slope shrub herbaceous area.Sorenson diversity index(β)of moss species is influenced by microenvironment and substrate.Concentrations of Al,Mg,Ca,Fe,K,and Ti are the largest in DB(2,990 to 73,210 mg kg^(-1)),followed by those in DF(2,900 to 61,890 mg kg^(-1)),and are the smallest in OC(690 to 32,240 mg kg^(-1)),which show that the three moss crusts have different bioaccumulation capacities.Metal contents in underlying soils of moss crusts are higher than the background levels.Bioaccumulation factor(BAF)of Al,Mg,Ca,Fe,and K in three moss crusts are decreased in the following order:DB>DF>OC.Single factor pollution index(Ps)and Nemero comprehensive pollution index(Pc)of six metal are much greater than 3,and the index of geoaccumulation(Igeo)(1geo<5)reveals that the soil environment is at moderately to seriously contaminated levels.Principal components analysis(PCA)shows that there is no significant correlation between p H value,and metal contents(Al,Mg,Fe,K and Ti),soil temperature(ST)and metal contents(Al,Mg,Fe,K and Ti).Soil humidity(SH)is negatively correlated with metal contents(Al,Mg,Fe,K and Ti).These three environmental factors have little effect on the distribution of metal.Result also reflects that DB moss is readily able to both tolerate and accumulate metal,which makes it a suitable bioindicator of multiple metal contamination in Wachangping bauxite tailing areas.
基金Project(5206800)supported by the National Natural Science Foundation of ChinaProject(2024JJA160096)supported by the Natural Science Foundation of Guangxi Province,China。
文摘Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water content and mud water separation rate was established to achieve efficient resource utilization,and the feasibility of foam lightweight soil(FLS)prepared from BT was investigated.The effects of industrial waste residues(fly ash and slag powder)on the properties of FLS were studied.Meanwhile,the micro-mechanisms were revealed by XRD,SEM-EDS,and TG-DSC.The results revealed that fly ash reduced the workability and compressive strength of FLS.Slag powder can significantly enhance the compressive strength of FLS,which increased by 18.60%-23.26%,17.07%-58.54% and 12.12%-52.12%,respectively.Besides,slag powder can improve the long-term water stability performance and enhance carbonation resistance.XRD and thermal analyses showed that adding fly ash decreased the hydration degree of FLS,leading to a decrease in the hydration products.Slag powder improved the pore structure and compacted the skeleton structure of FLS.This study would provide an effective way to realize the resource utilization of BT,fly ash,and slag powder,with certain socio-economic and environmental benefits.
基金supported by the National Natural Science Foundation of China (Nos.42077379 and 42177391)the Natural Science Foundation of Hunan Province,China (No.2022JJ20060)the Central South University InnovationDriven Research Program (No.2023CXQD065)。
文摘Recovery of microbial functions is one of the critical processes in the nutrient cycling of bauxite residue for improving revegetation.Straw is considered to be effective to increase microbial diversity and drive the development of the microbial community,but its effect on microbial carbon metabolism has not been illustrated.The present study evaluated the effects of phosphogypsum(PG),straw(SF)and phosphogypsum plus straw(PGSF)on physicochemical properties,enzyme activities,and microbial carbon metabolism activities in bauxite residue.After 180 days incubation,PG,SF and PGSF treatment significantly reduced the residue pH from 10.85 to 8.64,9.39 and 8.06,respectively.Compared to CK treatment,SF treatment significantly increased the content of total organic carbon(TOC)and organic carbon fractions(DOC,MBC,EOC,and POC).In addition,straw addition significantly increased glucosidase,cellulose,urease,and alkaline phosphatase by 7.2-9.1 times,5.8-7.1 times,11.1-12.5 times,and 1.1-2.2 times,respectively.The Biolog results showed that straw addition significantly increased microbial metabolic activity(AWCD)and diversity in bauxite residue.Redundancy analysis indicated total nitrogen(TN)and carbon fractions(POC,MBC and DOC)were the most important environmental factors affecting microbial metabolic activity and diversity in bauxite residue.These findings provided us with a biogeochemical perspective to reveal soil formation in bauxite residue and suggested that nutrient supplement and regulation of salinity-alkalinity benefit the establishment of microbial communities and functions in bauxite residue.
基金the National Natural Science Foundation of China(Nos.42177391,42077379)the Natural Science Foundation of Hunan Province,China(No.2022JJ20060)+1 种基金the Central South University Innovation-driven Research Program,China(No.2023CXQD065)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2023ZZTS0800).
文摘The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and microtopography.The results showed a significant decrease in Na_(2)O content(>30 wt.%)of FGD gypsum-treated bauxite residue after 30 min of mechanical ball milling.Mechanical ball milling resulted in differentiation of the elemental distribution,modification of the minerals in crystalline structure,and promotion in the dissolution of alkaline minerals,thus enhancing the acid neutralization capacity of bauxite residue.5 wt.%FGD gypsum combined with 30 min mechanical ball milling was optimal for the dealkalization of bauxite residue.
基金Supported by the PetroChina Science and Technology Innovation Fund Project(2021DQ02-1003)Basic Research Project for Central Universities(2022JCCXDC02).
文摘Through core observation,thin section identification,X-ray diffraction analysis,scanning electron microscopy,and low-temperature nitrogen adsorption and isothermal adsorption experiments,the lithology and pore characteristics of the Upper Carboniferous bauxite series in eastern Ordos Basin were analyzed to reveal the formation and evolution process of the bauxite reservoirs.A petrological nomenclature and classification scheme for bauxitic rocks based on three units(aluminum hydroxides,iron minerals and clay minerals)is proposed.It is found that bauxitic mudstone is in the form of dense massive and clastic structures,while the(clayey)bauxite is of dense massive,pisolite,oolite,porous soil and clastic structures.Both bauxitic mudstone and bauxite reservoirs develop dissolution pores,intercrystalline pores,and microfractures as the dominant gas storage space,with the porosity less than 10% and mesopores in dominance.The bauxite series in the North China Craton can be divided into five sections,i.e.,ferrilite(Shanxi-style iron ore,section A),bauxitic mudstone(section B),bauxite(section C),bauxite mudstone(debris-containing,section D)and dark mudstone-coal section(section E).The burrow/funnel filling,lenticular,layered/massive bauxite deposits occur separately in the karst platforms,gentle slopes and low-lying areas.The karst platforms and gentle slopes are conducive to surface water leaching,with strong karstification,well-developed pores,large reservoir thickness and good physical properties,but poor strata continuity.The low-lying areas have poor physical properties but relatively continuous and stable reservoirs.The gas enrichment in bauxites is jointly controlled by source rock,reservoir rock and fractures.This recognition provides geological basis for the exploration and development of natural gas in the Upper Carboniferous in the study area and similar bauxite systems.
基金supported by the National Natural Science Foundation of China(No.42307521)the China Postdoctoral Science Foundation(No.2023M742934)。
文摘A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was developed.The combination of recycled FeCl_(3)solution and EDTA activated desulfurization gypsum lowered the bauxite residue pH to 7.20.Moreover,it also improved the residual Ca state,with its contribution to the total exchangeable cations increased(68%-92%).Notably,the slow release of exchangeable Ca introduced through modified desulfurization gypsum induced a phase transition of the alkaline minerals.This treatment stabilized the dealkalization effect of bauxite residue via reducing its overall acid neutralization capacity in abating pH rebound.Hence,this approach can provide guidance for effectively utilizing desulfurization gypsum to achieve stable regulation of alkalinity in bauxite residue.
基金support provided by the National Natural Science Foundation of China(U21A20317).
文摘The low thermal conductivity and light mass of castables for tundish permanent linings are crucial for minimizing the heat loss of molten steel.In consideration of the low bulk density and thermal conductivity of pearlescent sand,the thermal insulation performance of castables was attempted to be improved by adding pearlescent sand.Pearlescent sand was modified to prevent the strength of its porous structure from deteriorating.The modification mechanism of pearlescent sand and the effect of pearlescent sand on the performance of bauxite castables were studied.The results suggested that the addition of the modified pearlescent sand significantly raised the apparent porosity and decreased the bulk density of bauxite castable.At 1000℃,the bulk density of more than 60%of the modified pearlescent sand-bauxite castable was only 2.03 g/cm^(3).The mechanical properties and thermal shock resistance of the modified pearlescent sand-bauxite castable were inferior to those of conventional bauxite castable but were adequate to meet the use conditions of casta-bles for tundish permanent linings.At high temperatures of 200-800℃,the thermal conductivity of more than 60%of the modified pearlescent sand-bauxite castable was smaller than that of conventional bauxite castable.The addition of the modified pearlescent sand can greatly reduce the thermal conductivity and bulk density of bauxite castable.
文摘Since their discovery, zeolites have generated significant interest in various technological fields, such as molecular sieves, ion exchangers, catalysts, and especially as adsorbents. This article focuses on characterizing the types of zeolites present in Sangarédi bauxite. To achieve this objective, we conducted a physico-chemical characterization (moisture, particle size, volumetric density, porosity) and determined the optimal conditions for activating the zeolite samples (15% H2SO4 concentration, L/S ratio of 2, temperature of 70˚C, duration of 3 hours). Techniques used to characterize the samples included desiccation gravimetry, mechanical sieving, X-ray fluorescence (atomic percentage), X-ray diffraction, BET method, and water pycnometry. Additionally, we assessed the adsorption capacity of zeolites activated by the elimination of methylene blue in an aqueous solution, which was selected as a model water pollutant. According to X-ray fluorescence and diffraction data, there are nine types of zeolite in Sangarédi bauxite, divided into five families. Regarding physical activation, a good porous structure was observed at a temperature of 300˚C to 340˚C for 4 hours. Above this range, material condensation occurs, leading to a sudden increase in mass loss, which can be explained by a change in their crystalline structure. After treatment with sulfuric acid, the activated samples showed an increase in specific surface area (from 72 to 130.25 m2∙g−1 on average) and porosity (from 0.07% to 0.3%), as well as an increased susceptibility to methylene blue discoloration (from 13.58% to 30.35%). These results confirm the improvement in the microporous structure and the formation of a more developed molecular sieve network. Thanks to the identified structural and textural characteristics, it can be concluded that the activated zeolites obtained are extremely reactive materials and can be used effectively in water treatment.
文摘The Sangarédi bauxite deposit in the Republic of Guinea contains several bauxite types depending on their litho-genetics. For rational and sustainable exploitation, determining the physical and mechanical properties of these different bauxite types is essential for mining companies. This paper presents a model for the physico-mechanical characterization of Sangarédi bauxites according to their litho-genetic type. Eight pits were drilled, and samples were collected from different layers at different depth intervals for each bauxite type. Physical and mechanical characterization tests were then carried out on 27 samples to determine the following parameters: water of absorption (%), compressive strength (kgf/cm2) and dynamic tensile strength (kgf/cm2). The effect of depth of sampling on these physico-mechanical parameters was evaluated. An average value of the parameters was made for each bauxite type. The results showed that the physico-mechanical characteristics of bauxites depend on the depth of sample collection, and the average value of the parameters constitutes the representative values of the bauxite type. Finally, a comparative study of the average value of the physico-mechanical parameters of the different bauxite types was carried out.
文摘The demand for useful ores has been growing steadily, especially since there is increasing interest in bauxite ores. This growing demand is prompting researchers to justify a large number of research projects on bauxites. The aim of this work is to characterize the Boundou-Waadé bauxite deposit. The proposed methodology is mainly based on sample collection, stratigraphic logs, cross-sections and geological maps. Samples were analyzed at the Compagnie des Bauxites de Guinée laboratory. Geochemical data were processed using statistical methods. Devonian sedimentary formations and Mesozoic dolerites characterize the study area. The Boundou-Waadé bauxite deposit was developed on Devonian and Mesozoic formations. Stratigraphic logs show the succession of formations, with the bedrock overlain by the alteration crust. The bauxitic zone, the transition zone and the ferruginous laterites are the subject of petrographic studies, with both zones (bauxitic and transition) containing some ferriplantite. Mineralogical analysis clearly shows that gibbsite, goethite, alumogoethite, rutile and clay minerals are present. The geochemical study of the major elements shows that as SiO2 and Fe2O3 content decreases, Al2O3 content increases and TiO2 and Al2O3 content increases in the same direction.
文摘The chemical and mineralogical composition of bauxite deposits is a key factor in the profitability of refining processes. The study of bauxites from the Saföfö site has assessed variations in chemical and mineralogical composition under various conditions, as well as the optimum conditions for their exploitation. The methodologies used in this study include experimental methods for determining moisture content, chemical composition, mineralogical composition, and specific density of bauxite. The results show significant variation in moisture content among the bauxite samples, with values ranging from 2.90% to 17.80%. The silica percentages in the samples range from 1.69% to 8.14%, while alumina percentages vary from 36.81% to 54.03%. After calcination, alumina oxide percentages range from 40% to 75%. After chemical activation, alumina oxides Al2O3 range from 40% to over 50%. Gibbsite is the most abundant mineral, accounting for about 60% - 70% of the total composition of the bauxite samples. Samples A to F have bulk densities varying between approximately 3.6 and 3.9. Sample B has the highest density, around 3.9, while sample C has the lowest, at around 3.5. Bauxite mining at the Saföfö site offers significant potential for the alumina industry, provided appropriate processing methods are selected to maximize quality and profitability while minimizing environmental impact.
基金Project(51374239)supported by the National Natural Science Foundation of China
文摘Reaction behaviors of sulfur and iron compounds in sodium aluminate solutions were investigated. The results show that iron compounds can remarkably remove the S2 but cannot get rid of S2Oc2-, SO^2- and SO4^-2 in sodium aluminate solutions. The removal efficiency of S^2- using ferrous compound and ferric compound can reach 86.10% and 92.70% respectively when the iron compounds were added with a molar ratio of 2：1 compared with the sulfur in liquors at 100℃. Moreover, several same compounds are formed in those two desulfurization processes with ferrous or ferric compounds, including erdite, hematite, amorphous ferrous sulfide, polymerized sulfur-iron compounds and ferric sulfate. The major difference between these two processes is that the erdite generated from ferrous compounds at the initial reaction stage will convert to a sodium-free product FeS2 at the subsequent stage.
基金Project(51304085)supported by the National Natural Science Foundation of ChinaProject(GJJ12363)supported by the Education Department of Jiangxi Province,ChinaProject(20142BAB216021)supported by the Natural Science Foundation of Jiangxi Province,China
文摘The flotation of diaspore and three kinds of silicate minerals, including kaolinite, illite and pyrophyllite, using an organosilicon cationic surfactant (TAS101) as collector and starch as depressant was investigated. The results show that both diaspore and aluminosilicate minerals float readily with organosilicon cationic collector TAS101 at pH values of 4 to 10. Starch has a strong depression effect for diaspore in the alkaline pH region but has little influence on the flotation of aluminosilicate minerals. It is possible to separate diaspore from aluminosilicate minerals using the organosilicon cationic collector and starch depressant. Further studies of bauxite ore flotation were also conducted, and the reverse flotation separation process was adopted. The concentrates with the mass ratio of Al2O3 to SiO2 of 9.58 and Al2O3 recovery of 83.34% are obtained from natural bauxite ore with the mass ratio of Al2O3 to SiO2 of 6.1 at pH value of 11 using the organosilicon cationic collector and starch depressant.
基金Projects(50974035,51074047,51004033) supported by the National Natural Science Foundation of ChinaProject(2008BAB34B01) supported by the National Science and Technology Pillar Program of China during the Eleventh Five-Year Plan Period+1 种基金Project (N100302005) supported by the National Higher-education Institution General Research and Development Funding,ChinaProject (2010AA03A405) supported by the Hi-tech Research and Development Program of China
文摘For the low-grade gibbsitic bauxite,the leaching rate of alumina is very low during the Bayer process.The acid leaching method is attracting more attention,and the hydrochloric acid leaching was developed rapidly.The mineral composition and chemical composition were investigated by X-ray diffraction analysis and semi-quantitative analysis.The thermodynamics of leaching process was analyzed.The results show that the major minerals in the bauxite are gibbsite,secondly goethite and quartz,anatase and so on.The acid leaching reactions of the bauxite would be thermodynamically easy and completed.Under the conditions that ore granularity is less than-55 μm,the L/S ratio is 100：7,and the leaching temperature is 373-383 K,the leaching time is 120 min and the concentration of HCl is 10%,both the leaching rates of Al and Fe are over 95%.The main composition of leaching slag is SiO2 which is easy for comprehensive utilization.
基金Project(20971041) supported by the National Natural Science Foundation of ChinaProject(09B032) supported by Scientific Research Fund of Hunan Provincial Education Department,China
文摘The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.
