氯化铵浸出镁还原渣提钙工艺

皮江法炼镁过程产生大量的镁还原渣,堆存过程中易造成土壤碱化和板结等环境问题,在消纳方面主要用于制备水泥、建筑砖和脱硫剂,综合利用价值低。基于此,提出氯化铵浸出镁还原渣工艺路线,该工艺可以提取和分离镁还原渣中的钙、硅等元素,使镁还原渣成为钙源和硅源,实现镁还原渣的零排放和高值化利用。现针对工艺中的浸出过程,研究在各单因素条件下钙的浸出率及浸出渣物相,得出以下结论:氯化铵能对镁还原渣中钙进行选择性浸出,其浸出率与反应温度、氯化铵浓度、液固体积质量比等密切相关;浸出率随氯化铵浓度、液固体积质量比的增大而增大,随温度的升高先增加后减小;较佳浸出工艺条件为反应温度25℃、氯化铵浓度15%、液固体积质量比40∶1,该条件下,钙的浸出率达到88.7%;浸出渣物相主要为氧化镁、碳酸钙、二氧化硅等物质,通过洗涤工序可以获得较为纯净的含硅原料。

机械活化对氧化锌矿碱法浸出及其物化性质的影响

研究了不同活化时间、活化方式对云南兰坪低品位氧化锌矿碱法浸出的影响.结果表明,当浸出液NH4Cl浓度2.0mol/L、NH3·H2O浓度1mol/L、温度30℃、浸出液与浸出矿样液固比为10L/g时,未活化矿样浸出90min浸出率仅为60.08%,而活化90min矿样浸出90min的浸出率为69.36%,为可浸出含锌物相的103.97%;先磨后浸的强化效果优于边磨边浸.不同活化时间、活化方式不仅造成矿物的形貌、粒度分布不同,而且使矿样在球磨过程中的物相转化存在差异:活化与浸出步骤分离时,球磨过程发生了机械化学反应,矿样中ZnS被氧化成利于浸出的物相,从而比两步骤合并的浸出效果好.

响应曲面法优化承钢含钒钢渣浸出负组元钙的试验研究

针对承德某含钒钢渣中钙组元含量高,钒难以浸出的问题,采用氯化铵浸出方式对其进行了提钒预处理研究。通过XRD分析和热力学研究发现,在氯化铵浸出过程中铁酸二钙、硅酸二钙、硅酸三钙为浸出过程的主要反应对象。单因素试验的最佳条件下,钙组元的浸出率可达50.03%。在单因素试验的基础上,通过Design-expert软件设计正交试验,结合响应曲面法考察了因素之间的交互作用及不同因素对试验影响的显著程度,并优化试验指标。结果表明,磨矿细度、浸出温度、浸出时间之间存在显著交互作用;因素的显著程度方面,浸出温度>磨矿细度>浸出时间>浸出液固比;重新优化试验后,在细度-74μm占80%、温度100℃、时间4 h、液固比4的条件下,钙组元的浸出率可达到60.12%,可有效提高氯铵浸钙的试验指标。

Leaching kinetics of zinc silicate in ammonium chloride solution

The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed （150？400 r/min）, leaching temperature （95-108 ℃, particle size of zinc silicate （61-150 μm） and the concentration of ammonium chloride （3.5-5.5 mol/L） on leaching rate of zinc were studied. The results show that decreasing the particle size of zinc silicate and increasing the leaching temperature and concentration of ammonium chloride can obviously enhance the leaching rate of zinc. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control can well describe the zinc leaching kinetics. The apparent activation energy of the leaching reaction is 161.26 kJ/mol and the reaction order with respect to ammonium chloride is 3.5.

单宁锗精矿中回收铅锌及单宁的试验研究

单宁锗精矿中存在有大量的锌、铅等有价金属,造成单宁锗含锗品位低的同时,也造成了有价金属的大量流失。研究过程中采用氯化铵低温浸出、草酸回收单宁,可以使单宁锗中的锌回收率达到92%,铅回收率达到93%,锗品位提高5倍以上,单宁经酸化处理进行沉锗,经计算回收率达到60%。

Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue

This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride treatment.The results showed that the pH of bauxite residue decreased from 10.49 to 8.93,total alkaline anion(HCO3^-,CO3^2-,OH^-,AlO2^-)concentration reduced from 38.89 to 25.50 mmol/L,leaching rate of soluble sodium was 80.86%with ammonium chloride addition of 0.75%,liquid/solid(L/S)ratio of 3(mL/g),temperature of 30°C and reaction time of 18 h;L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of sodium.Furthermore,ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive structure.The findings of this work will contribute to achieve soil-formation of bauxite residue.

Thermodynamics of solubility of Cu_2(OH)_2CO_3 in ammonia-ammonium chloride-ethylenediamine(En)-water system

In order to decrease the evaporating rate of ammonia and increase the solubility of copper in the solution,ethylenediamine was added into the ammonia-ammonium chloride system to leach the copper-containing oxide ores.The thermodynamic model was constructed and the solubility of malachite Cu2(OH)2CO3 in the ammonia-ammonium chloride-ethylenediamine(En)-water system was calculated using the exponential computation method based on both mass balance and charge balance.It is found that the solubility of copper can be increased and the free ammonia concentration can be decreased by submitting partial ammonia with ethylenediamine.The lower free ammonia concentration in the solution is a guarantee to the lower evaporating rate of ammonia.The conditions of malachite Cu2(OH)2CO3 converting to atacamite Cu(OH)1.5Cl0.5 were also studied.A group of experiments were designed to validate the veracity of the results of the thermodynamic calculation.It is found that the thermodynamic model is reliable and it can guide the leaching process.

Dissolution kinetics of low grade complex copper ore in ammonia-ammonium chloride solution

The leaching kinetics of Tang-dan refractory low grade complex copper ore was investigated in ammonia-ammonium chloride solution.The concentration of ammonia and ammonium chloride,the ore particle size,the solid-to-liquid ratio and the temperature were chosen as parameters in the experiments.The results show that temperature,concentration of ammonia and ammonium chloride have favorable influence on the leaching rate of copper oxide ores.But,leaching rate decreases with increasing particle size and solid-to-liquid ratio.The leaching process is controlled by the diffusion of the lixiviant and the activation energy is determined to be 23.279 kJ/mol.An equation was also proposed to describe the leaching kinetics.