含锗冶炼渣富集锗的试验研究

针对含有铅、锌、铜、铁及锗的冶炼渣提出了"硫酸氧化浸出—预中和—丹宁沉锗"的流程分离富集其中的锗。其中考察了硫酸氧化浸出的三种方法:氧压酸浸出、过硫酸钠氧化浸出、双氧水氧化浸出,得出了最佳条件,经过丹宁沉锗后,可使沉锗渣中锗的品位提高至9%以上。

从镍钴复合盐中提取镍钴

针对从古巴进口的含钴原料(镍钴复合盐)的特点,提出了一个新的提钴技术"加温水洗——碱沉镍钴及硫酸氧化浸出",并且通过实验得到含镍钴物料均能并入某公司现有流程中,钴直收率68.42%,钴回收率92.35%,镍回收率97.4%,比1998年处理镍钴复合盐钴直收率提高了14.52%,钴回收率提高了4.31%,镍回收率提高了10.84%。但是该流程难于除氨。

Oxidative leaching behavior of metalliferous black shale in acidic solution using persulfate as oxidant

The oxidative dissolution of metalliferous black shale in sulfuric acid solution using sodium persulfate as an oxidant was investigated. The effects of leaching factors including leaching temperature, leaching time, stirring speed, initial concentration of sodium persulfate and sulfuric acid and particle size on the leaching rate were studied as well. The leaching kinetics of molybdenum, nickel and iron from metalliferous black shale shows that the leaching rate is controlled by a chemical reaction through a layer on the unreacted shrinking core. The leaching process follows the kinetics model 1-（1-a）^1/3=kt with apparent activation energies of 34.50, 43.14 and 71.79 kJ/mol for Mo, Ni and Fe, respectively. The reaction orders in sodium persulfate are 0.80, 1.01 and 0.75 for molybdenum, nickel and iron, respectively, while in sulfuric acid, these orders are 0.45, 0.75 and 0.50 for molybdenum, nickel and iron, respectively. In addition, the reaction mechanism for the dissolution of the metalliferous black shale was discussed.

Effect of pH values on extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.

Acid leaching decarbonization and following pressure oxidation of carbonic refractory gold ore

Carbonate decomposition of carbonic refractory gold ore and the following pressure oxidation were studied.In the carbonate decomposition procedure,the effects of liquid-to-solid ratio and reaction time on decomposition ratio of carbonate were investigated.The experimental result shows that the decomposition ratio of carbonate is 98.24%under the conditions of liquid-to-solid ratio of 5:1,Fe^(3+)concentration of 20 g/L,sulfuric acid concentration of 20 g/L,reaction temperature of 80 ℃ and reaction time of 2 h.Then,the slurry obtained from carbonate decomposition was put into the titanium autoclave for pressure oxidation leaching.Effects of liquid-to-solid ratio,temperature,time and oxygen partial pressure on sulfur oxidation ratio were studied during pressure oxidation.With the prolonged time,pyrite and arsenopyrite are oxidized to ferric subsulfate,hydrated ferric sulfate and jarosite,resulting in the increasing residue ratio.The residue ratio and the sulfur content in the residue can be decreased by ferric subsulfate dissolution.The oxidation ratio of the sulfur is 99.35% under the conditions of oxidation time of 4 h,temperature of 210 ℃,oxygen partial pressure of 0.8 MPa and stirring speed of 600 r/min.

Separation and recovery of copper in Cu-As-bearing copper electrorefining black slime by oxidation acid leaching and sulfide precipitation

A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and selective sulfide precipitation of Cu from the leachate. The effects of various process parameters on the leaching and precipitation of Cu and As were investigated. At the first stage, Cu extraction of 95.2% and As extraction of 97.6% were obtained at 80 ℃ after 4 h with initial H2 SO4 concentration of 1.0 mol/L and liquid-to-solid ratio of 10 mL/g. In addition, the leaching kinetics of Cu and As was successfully reproduced by the Avrami model, and the apparent activation energies were found to be 33.6 and 35.1 kJ/mol for the Cu and As leaching reaction, respectively, suggesting a combination of chemical reaction and diffusion control. During the selective sulfide precipitation, about 99.4% Cu was recovered as CuS, while only 0.1% As was precipitated under the optimal conditions using sulfide-to-copper ratio of 2.4:1, time of 1.5 h and temperature of 25 ℃.

Pressure leaching of zinc silicate ore in sulfuric acid medium

Zinc silicate ore was characterized mineralogically and the results showed that zinc exists mainly as hemimorphite and smithsonite in the sample.Sulfuric acid pressure leaching of zinc silicate ore was carried out to assess the effect of particle size,sulfuric acid concentration,pressure,reaction time and temperature on the extraction of zinc and the dissolution of silica.Under the optimum conditions employed,up to 99.25% of zinc extraction and 0.20% silica dissolution are obtained.The main minerals in leaching residue are quartz and small amounts of undissolved oxide minerals of iron,lead and aluminum are associated with quartz.

Synthesis and alumina leaching mechanism of calcium sulphoaluminate

Calcium sulphoaluminate(3CaO·3Al2O3·CaSO4,abbreviated as C4A3S)was synthesized by sintering at1375°C for2h with analytically pure carbonate calcium,alumina and dihydrate calcium sulfate.The crystal structure of C4A3S was characterized by XRD,SEM and TEM.Alumina leaching properties in Na2CO3solution were studied,and the leaching mechanism was investigated by means of Raman spectrum and XRD.The results show that C4A3S has porous morphology.The polycrystallines and single crystals coexist in C4A3S and grow along different directions.The alumina leaching rate of C4A3S is98.41%,which is higher than that of12CaO·7Al2O3under the optimal condition.The aluminum and sulfur elements exist in the leaching solution in the form of Al(OH)4and24SO,respectively,and the calcium exists as CaCO3in the leaching residues.

酸泥湿法回收汞硒试验研究

针对锌冶炼所产制酸酸泥因含汞硒较低(Hg 2.06%,Se 6.9%),直接外售无经济效益的现状,公司采用"硫酸+氯酸钠氧化浸出-次亚磷酸还原沉汞-硫脲+亚硫酸钠还原沉硒"工艺对此酸泥进行了回收汞、硒的试验研究。结果表明在各试验工序的最佳工艺条件下,所得汞渣含汞78.37%,汞总回收率95.06%,粗硒含硒97.82%,硒总回收率90.51%。该工艺回收汞硒处理成本低,各工序仅有微量有害气体,可进行环保处理,对环境不会造成污染,若工业化应用,可取得较好经济效益。

Mechanism of Chalcopyrite Leaching in Oxidative Sulphuric Acid Solution

The mechanism of the leaching process of chalcopyrite concentrate with sodium nitrate in sulphuric acid solution were studied and discussed. Chemical reactions of leaching and their thermodynamic probabilities are predicted based on the calculated Gibbs energies and analysis of E-pH diagrams. Experimental data, thermodynamic analysis, chemical, XRD, and SEM/EDX analyses of concentrate and the leach residues, were performed to develop a better understanding of the chemical reactions that took place in the system. Elemental sulphur was formed as the main leaching product, precipitated at the particle surfaces and tended to inhibit the leaching rate.