Potassium hydroxide(KOH)was introduced into the molybdenite roasting process to convert molybdenum(Mo)and sulfur(S)into water-soluble potassium molybdate(K_(2)MoO_(4))and potassium sulfate(K_(2)SO_(4)).Roasting with a...Potassium hydroxide(KOH)was introduced into the molybdenite roasting process to convert molybdenum(Mo)and sulfur(S)into water-soluble potassium molybdate(K_(2)MoO_(4))and potassium sulfate(K_(2)SO_(4)).Roasting with a 1.8-fold excess of KOH at 400℃ for 3 h enabled the leaching of over 99%of Mo from the molybdenum calcine using water.A precipitation method involving potassium–magnesium(K-Mg)salts was proposed for impurity removal.Under the conditions of pH 11,30℃,excess coefficient of 1.7 for Mg salts,and a duration of 1 h,98.37%of phosphorus(P)was removed from the K_(2)MoO_(4) solution.With post-purification,over 99%of Mo crystallized upon adjustment of pH to 1.Subsequently,S and K were recovered as K_(2)SO_(4) fertilizer from the crystalline mother liquor.An environmentally sustainable approach was proposed to conduct molybdenite production and ensure the efficient recovery of both Mo and S.展开更多
A transformative beryllium metallurgy theory and method was proposed based on the low-temperature dissociation of hydrofluoric acid and purification by exploiting the large difference of fluoride solubility.Hydrofluor...A transformative beryllium metallurgy theory and method was proposed based on the low-temperature dissociation of hydrofluoric acid and purification by exploiting the large difference of fluoride solubility.Hydrofluoric acid can quickly dissociate berylum ore powder directly at low or room temperature with more than 99%dissociation rate.The solubility of AlF_(3),FeF_(3) CrF_(3) and MgF_(2),is low.Coupled with common ion effect,99.9%-purity beryllium products can be prepared without chemical purification.For high-purity beryllium products of grade 4N or higher,they can be prepared through the superior property that the pH intervals of iron,chromium,and other hydroxide precipitates are distinctly different from those corresponding to Be(OH)_(2),precipitates.This new method can be used to prepare most of the beryllium products that are prepared by modern beryllium metallurgy.展开更多
The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. T...The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidationtemperature of MoS2 is 450℃, while the formation of CaMoO4 and CaSO4 occurs above 500℃. The whole calcification reactionsare nearly completed between 600 and 650℃. However, raising the temperature further helps for the formation of CaMoO4 but isdisadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows theorder： Ca（OH）2〉CaO〉CaCO3. With increasing the dosage of Ca（OH）2, the molybdenum retention rate and sulfur-fixing rate rise, butexcessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca（OH）2 to molybdenumconcentrate is 1：1. When roasted at 650 ℃ for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grademolybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% withcalcines being leached by sulphuric acid.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52174340)the National Key Research and Development Project of China(No.2022YFC2904505)the Hunan FURONG Scholars Project and the Basic Science Centre of the National Natural Science Foundation of China(No.72088101)。
文摘Potassium hydroxide(KOH)was introduced into the molybdenite roasting process to convert molybdenum(Mo)and sulfur(S)into water-soluble potassium molybdate(K_(2)MoO_(4))and potassium sulfate(K_(2)SO_(4)).Roasting with a 1.8-fold excess of KOH at 400℃ for 3 h enabled the leaching of over 99%of Mo from the molybdenum calcine using water.A precipitation method involving potassium–magnesium(K-Mg)salts was proposed for impurity removal.Under the conditions of pH 11,30℃,excess coefficient of 1.7 for Mg salts,and a duration of 1 h,98.37%of phosphorus(P)was removed from the K_(2)MoO_(4) solution.With post-purification,over 99%of Mo crystallized upon adjustment of pH to 1.Subsequently,S and K were recovered as K_(2)SO_(4) fertilizer from the crystalline mother liquor.An environmentally sustainable approach was proposed to conduct molybdenite production and ensure the efficient recovery of both Mo and S.
基金National Key Research and Development Program of China(2021YFC2902301,2021YFC2902302)。
文摘A transformative beryllium metallurgy theory and method was proposed based on the low-temperature dissociation of hydrofluoric acid and purification by exploiting the large difference of fluoride solubility.Hydrofluoric acid can quickly dissociate berylum ore powder directly at low or room temperature with more than 99%dissociation rate.The solubility of AlF_(3),FeF_(3) CrF_(3) and MgF_(2),is low.Coupled with common ion effect,99.9%-purity beryllium products can be prepared without chemical purification.For high-purity beryllium products of grade 4N or higher,they can be prepared through the superior property that the pH intervals of iron,chromium,and other hydroxide precipitates are distinctly different from those corresponding to Be(OH)_(2),precipitates.This new method can be used to prepare most of the beryllium products that are prepared by modern beryllium metallurgy.
基金Project(51304245)supported by the National Natural Science Foundation of ChinaProject(2014T70691)supported by the Postdoctoral Science Foundation of China+1 种基金Project(2015CX005)supported by the Innovation Driven Plan of Central South University,ChinaProject supported by the Hunan Provincial Co-innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China
文摘The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidationtemperature of MoS2 is 450℃, while the formation of CaMoO4 and CaSO4 occurs above 500℃. The whole calcification reactionsare nearly completed between 600 and 650℃. However, raising the temperature further helps for the formation of CaMoO4 but isdisadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows theorder： Ca（OH）2〉CaO〉CaCO3. With increasing the dosage of Ca（OH）2, the molybdenum retention rate and sulfur-fixing rate rise, butexcessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca（OH）2 to molybdenumconcentrate is 1：1. When roasted at 650 ℃ for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grademolybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% withcalcines being leached by sulphuric acid.
