Activation pretreatment of Cr-containing limonitic laterite ores by NaOH roasting to remove Cr, Al, and Si, as well as its effect on Ni and Co extraction in the subsequent pressure acid leaching process was investigat...Activation pretreatment of Cr-containing limonitic laterite ores by NaOH roasting to remove Cr, Al, and Si, as well as its effect on Ni and Co extraction in the subsequent pressure acid leaching process was investigated. Characterization results of X-ray diffraction （XRD） and scanning electron microscopy/X-ray energy dispersive spectroscopy （SEM/XEDS） show that goethite is the major Ni-bearing mineral, and chromite is the minor one. Experimental results show that the leaching rates of Cr, Al, and Si are 95.6wt%, 83.8wt%, and 40.1wt%, respectively, under the optimal alkali-roasting conditions. Compared with the direct pressure acid leaching of laterite ores, the leaching rates of Ni and Co increase from 80.1wt% to 96.9wt% and 70.2wt% to 95.1wt% after pretreatment, respectively. Meanwhile, the grade of acid leaching iron residues increases from 54.4wt% to 62.5wt%, and these residues with low Cr content are more suitable raw materials for iron making.展开更多
研究了不同浓度NaOH(质量分数为2%,4%和6%)预处理对油菜秸秆厌氧消化产气性能的影响。结果表明:6%NaOH预处理组累积产甲烷量达到了12 337 m L,单位VS产甲烷量为264.3 m L/g,较未处理组、2%NaOH预处理组和4%NaOH预处理组分别提高了38.0%,...研究了不同浓度NaOH(质量分数为2%,4%和6%)预处理对油菜秸秆厌氧消化产气性能的影响。结果表明:6%NaOH预处理组累积产甲烷量达到了12 337 m L,单位VS产甲烷量为264.3 m L/g,较未处理组、2%NaOH预处理组和4%NaOH预处理组分别提高了38.0%,10.2%和7.00%;T90为23 d,较未处理组、2%NaOH预处理组和4%NaOH预处理组分别提高了19,12,5 d;氨氮为742 mg/L,碱度为7 400 mg/L,p H为7.42,三者均在适宜范围内。综合考虑,6%NaOH预处理组的油菜秸秆厌氧消化产气效率较高。展开更多
The newly developed green leaching processes for chromium, lead and gold extraction from ores or concentrates are described. The chromium is extracted from the iron chromite ore with fused sodium hydroxide at 500-550...The newly developed green leaching processes for chromium, lead and gold extraction from ores or concentrates are described. The chromium is extracted from the iron chromite ore with fused sodium hydroxide at 500-550℃ as sodium chromate. The galena in lead sulfide concentrate is converted into lead carbonate in ammonium or sodium carbonate solution at 50-80℃ followed by the separation of lead carbonate formed from the unconverted sulfide ores by flotation. Gold associated with sulfide ore (such as pyrite and chalcopyrite) can be extracted into sodium thiosulfate solution without any pretreatment such as roasting, high pressure aqueous oxidation or bacteria pre-leaching.展开更多
基金supported by the National Key Technology R&D Program (No.2011BAC06B07)
文摘Activation pretreatment of Cr-containing limonitic laterite ores by NaOH roasting to remove Cr, Al, and Si, as well as its effect on Ni and Co extraction in the subsequent pressure acid leaching process was investigated. Characterization results of X-ray diffraction （XRD） and scanning electron microscopy/X-ray energy dispersive spectroscopy （SEM/XEDS） show that goethite is the major Ni-bearing mineral, and chromite is the minor one. Experimental results show that the leaching rates of Cr, Al, and Si are 95.6wt%, 83.8wt%, and 40.1wt%, respectively, under the optimal alkali-roasting conditions. Compared with the direct pressure acid leaching of laterite ores, the leaching rates of Ni and Co increase from 80.1wt% to 96.9wt% and 70.2wt% to 95.1wt% after pretreatment, respectively. Meanwhile, the grade of acid leaching iron residues increases from 54.4wt% to 62.5wt%, and these residues with low Cr content are more suitable raw materials for iron making.
文摘The newly developed green leaching processes for chromium, lead and gold extraction from ores or concentrates are described. The chromium is extracted from the iron chromite ore with fused sodium hydroxide at 500-550℃ as sodium chromate. The galena in lead sulfide concentrate is converted into lead carbonate in ammonium or sodium carbonate solution at 50-80℃ followed by the separation of lead carbonate formed from the unconverted sulfide ores by flotation. Gold associated with sulfide ore (such as pyrite and chalcopyrite) can be extracted into sodium thiosulfate solution without any pretreatment such as roasting, high pressure aqueous oxidation or bacteria pre-leaching.
