The recovery of zinc from low-grade zinc oxide ores with solvent extraction-electrowinning technique was investigated by using D2EHPA as extractant and 260 # kerosene as diluent. The results show that it is possible t...The recovery of zinc from low-grade zinc oxide ores with solvent extraction-electrowinning technique was investigated by using D2EHPA as extractant and 260 # kerosene as diluent. The results show that it is possible to selectively leach zinc from the ores by heap leaching. The zinc concentration of leach solution in the first leaching cycle is 32.57 g/L, and in the sixteenth cycle the zinc concentration is 8.27g/L after solvent extraction. The leaching solution is subjected to solvent extraction, scrubbing and selective stripping for enrichment of zinc and removal of impurities. The pregnant zinc sulfate solution produced from the stripping cycle is suitable for zinc electrowinning. Extra-pure zinc metal was obtained in the electrowinning test under conventional conditions.展开更多
Palm fatty acid distillate （PFAD）, a by-product of deodorization in palm oil refining, contains about 0.7%-1% vitamin E. The advantage of PFAD over other vitamin E sources is higher amount of tocotrienols than that ...Palm fatty acid distillate （PFAD）, a by-product of deodorization in palm oil refining, contains about 0.7%-1% vitamin E. The advantage of PFAD over other vitamin E sources is higher amount of tocotrienols than that of tocopherols. Vitamin E purification of unsaponiable matter of PFAD was aimed to remove other impurities to obtain high vitamin E concentration, mainly tocotrienols. This research used low temperature solvent crystallization to purify vitamin E. To optimize response of vitamin concentration, a response surface method was applied with three factors, i.e., the ratio between solvent and unsaponifiable matter （A）, crystallization temperature （B）, and crystallization time （C）. The relation of three factors was quadratic with equation Y = -128.54361 ＋ 41.33904A - 0.87995B ＋ 1.58941C ＋ 0.00290AB - 0.044324AC ＋ 0.00120BC - 3.33113A2 - 0.039535B2 - 0.02710C2. The optimum crystallization condition was obtained at ratio of solventto unsaponifiable matter of 6.04：1, crystallization temperature of-10.54 ℃, and crystallization time of 24.16 hours. Vitamin E enriched fraction from optimum crystallization conditions contained vitamin E of 20.13% （w/w）.展开更多
In order to economically recover the copper from the low grade copper ores, a bioleaching solvent extraction electrowinning plant with a design capacity of 2 000 t cathode copper per year in Dexing Copper Mine was ope...In order to economically recover the copper from the low grade copper ores, a bioleaching solvent extraction electrowinning plant with a design capacity of 2 000 t cathode copper per year in Dexing Copper Mine was operated in September, 1997. The results during the 10 month period of the industrial copper dump leaching have been obtained and the approaches have been carried out to enhance the copper dissolution from the waste rocks. The overall operation flowsheet is depicted. The problems confronted in the process and possible way for improving are discussed.展开更多
文摘The recovery of zinc from low-grade zinc oxide ores with solvent extraction-electrowinning technique was investigated by using D2EHPA as extractant and 260 # kerosene as diluent. The results show that it is possible to selectively leach zinc from the ores by heap leaching. The zinc concentration of leach solution in the first leaching cycle is 32.57 g/L, and in the sixteenth cycle the zinc concentration is 8.27g/L after solvent extraction. The leaching solution is subjected to solvent extraction, scrubbing and selective stripping for enrichment of zinc and removal of impurities. The pregnant zinc sulfate solution produced from the stripping cycle is suitable for zinc electrowinning. Extra-pure zinc metal was obtained in the electrowinning test under conventional conditions.
文摘Palm fatty acid distillate （PFAD）, a by-product of deodorization in palm oil refining, contains about 0.7%-1% vitamin E. The advantage of PFAD over other vitamin E sources is higher amount of tocotrienols than that of tocopherols. Vitamin E purification of unsaponiable matter of PFAD was aimed to remove other impurities to obtain high vitamin E concentration, mainly tocotrienols. This research used low temperature solvent crystallization to purify vitamin E. To optimize response of vitamin concentration, a response surface method was applied with three factors, i.e., the ratio between solvent and unsaponifiable matter （A）, crystallization temperature （B）, and crystallization time （C）. The relation of three factors was quadratic with equation Y = -128.54361 ＋ 41.33904A - 0.87995B ＋ 1.58941C ＋ 0.00290AB - 0.044324AC ＋ 0.00120BC - 3.33113A2 - 0.039535B2 - 0.02710C2. The optimum crystallization condition was obtained at ratio of solventto unsaponifiable matter of 6.04：1, crystallization temperature of-10.54 ℃, and crystallization time of 24.16 hours. Vitamin E enriched fraction from optimum crystallization conditions contained vitamin E of 20.13% （w/w）.
文摘In order to economically recover the copper from the low grade copper ores, a bioleaching solvent extraction electrowinning plant with a design capacity of 2 000 t cathode copper per year in Dexing Copper Mine was operated in September, 1997. The results during the 10 month period of the industrial copper dump leaching have been obtained and the approaches have been carried out to enhance the copper dissolution from the waste rocks. The overall operation flowsheet is depicted. The problems confronted in the process and possible way for improving are discussed.
文摘用氯化胆碱/尿素低共熔溶剂改性茶叶渣,研究其对苯酚废水的吸附性能,探讨了不同苯酚初始浓度、不同吸附剂用量、不同pH对吸附过程的影响,并利用等温吸附模型对吸附机理进行分析。结果表明,吸附的最好条件为苯酚初始浓度20 mg L^(-1),吸附剂用量为4 g L^(-1),pH=6,吸附率可达90%以上。茶叶渣吸附过程符合Freundlich等温模型,表明该过程是在非均相表面发生的多层吸附。
