氰化物水解除氰动力学研究

介绍了氰化钠水解除氰的动力学试验 ,揭示了水解反应速度常数随温度的变化规律 ,同时建立了氰化物水解除氰率、水解温度及反应时间之间的数学模型。     

加活性炭水解除氰的动力学研究

在氰化物溶液中加入了活性炭后详细地进行了水解动力学试验，以寻求加炭后水解反应速率常数随温度的变化规律。同时建立了氰化物溶液加炭后的除氰率与水解温度与反应时间之间数学模型。     

氧化锌浸出系统中高锑溶液的除锑实验研究

采用先氧化后水解沉淀法去除氧化锌浸出系统中高锑溶液的杂质锑。考察了高锑溶液pH值、反应温度、反应时间、高锰酸钾用量等因素对除锑率的影响。结果表明,保持溶液温度在50℃左右,pH 3.8,按理论量1.4倍加入高锰酸钾,反应时间45min,锑的去除率达94%,溶液中剩余的锑含量小于2mg/L。     

用高温水解法从钴铁浸溶结晶物中分离钻的研究

在管状好的固定床层中进行了钴铁合金浸溶物的高温水解速率测定与钴铁分离的试验。反应过程由界面化学反应与内扩散两环节组成。界面化学反应控制阶段的表观速率常数表观后化能等于８０．５７ｋＪ／ｍｏｌ。讨论了温度、水分压比和反应时间对钴回收率与钴铁分离效果的影响。确定了最佳条件是４００℃以下，水分压比小于０．１１，物料极度为＋２－４ｍｍ，水解时间不应超过４５ｍｉｎ。     

钛液水解产品质量与生产效率调控方法

这是一篇冶金工程领域的论文。为了提高水解产物的性能和产量，本文研究了水解产物的平均粒径与水解速率之间的耦合效应。采用响应面法建立了水解温度、钛液初始浓度、钛液F值、水解时间、平均粒径和水解速率的耦合数学模型。通过方差分析和失真分析，验证了数学模型的适用性。水解温度对平均粒径有明显影响，而且平均粒径与水解温度成反比。而水解温度对水解速率的影响最大，其次是初始钛浓度、钛液F值和水解时间。随着水解温度的升高，水解速率会继续降低。以2μm平均粒径和较高水解率为优化目标，实验结果表明，2μm平均粒径和水解率预测值与实验值的误差分别为2.86%和2.01%，再次验证了模型的适用性。研究结果为工业生产中钛液水解过程的预测、控制和优化提供了理论支持。     

二氧化氯氧化法处理含氰废水试验研究

针对某含氰含铜废液,采用二氧化氯氧化法脱除废液中氰,再用硫化法沉淀回收溶液中铜。结果表明,二氧化氯氧化法除氰合理工艺条件为: 反应温度25 ℃、溶液初始pH=9.5、反应时间60 min、二氧化氯气体流速60 mL/min,此时除氰率达到96%以上; 硫化沉淀法回收除氰后液中的铜,合理工艺条件为: 反应温度25 ℃、反应时间60 min、溶液初始pH=3、搅拌速度300 r/min、硫化钠用量为理论量3倍,此时沉铜率达到93%以上。     

从砷锑烟尘中回收锑的实验研究

采用氯化—水解法从砷锑烟尘制取三氧化二锑,在砷锑烟尘经酸浸脱砷工序后,分别考察了水解时间、水解温度、稀释比对锑水解的影响和稀释比、氨水过量系数、反应时间及反应温度对氯氧锑脱氯的影响。结果表明,在稀释比为6∶1、温度为25℃和水解时间为1.5 h条件下水解,及在液固比为1.5∶1、反应温度为25℃、水解时间为0.5 h和氨水过量系数为1.5条件下脱氯,最后可得到砷锑烟尘中锑的回收率达到80.99%。     

从砷锑烟尘中回收锑的试验研究

采用氯化—水解法从砷锑烟尘制取三氧化二锑,在砷锑烟尘经酸浸脱砷工序后,分别考察了水解时间、水解温度、稀释比对锑水解的影响和稀释比、氨水过量系数、反应时间及反应温度对氯氧锑脱氯的影响。结果表明,在稀释比为6∶1、温度为25℃和水解时间为1.5 h条件下水解,及在液固比为1.5∶1、反应温度为25℃、水解时间为0.5 h和氨水过量系数为1.5条件下脱氯,最后可得到砷锑烟尘中锑的回收率达到80.99%。     

浅色导电云母粉研制

以SnCl4 ·5H2 O和SbCl3为原料 ,采用化学共沉淀法在超细云母粉表面包覆二氧化锡掺杂锑 ,形成导电层。运用热分析仪和粒度分布仪对粉体进行了表征。研究了水解 pH值、水解温度、氧化锡的包覆率、m(SnCl4 ·5H2 O) /m(SbCl3)、反应时间和热处理温度对导电云母体积电阻率和颜色的影响 ,并对实验结果进行了讨论     

氧化锌浸出系统中高锑溶液的除锑试验研究

采用先氧化后水解沉淀法去除氧化锌浸出系统中高锑溶液的杂质锑。考察了高锑溶液pH值、反应温度、反应时间、高锰酸钾用量等因素对除锑率的影响。结果表明,保持溶液温度在50℃左右,pH 3.8,按理论量1.4倍加入高锰酸钾,反应时间45min,锑的去除率达94%,溶液中剩余的锑含量小于2mg/L。     

The mechanism of leaching of gold from refractory ores

Refractory gold ores commonly contain free gold, submicroscopic gold, base metal sulphides, pyrite, pyrrhorite, labile sulphides and carbonaceous material. The analysis of gold deportment with the diagnostic leaching technique has opened a research field to gain more insight into the fundamentals of the kinetic behaviour of gold dissolution from refractory ores. Hence, more detailed studies on the kinetics of the reactions that occur during leaching with cyanide are now possible.Previous research work has indicated that the dissolution rate of gold during cyanidation becomes depressed after a certain time with no further increase in the rate. However, a second noticeable increase in the gold dissolution rate has been observed after a leaching time of 5 to 12 hours during some of the cyanidations, following the destruction of a mineral with the diagnostic leaching technique. If such a second increase in dissolution rate does not occur, the re-leaching of the filtered solids with a fresh cyanide solution yields an additional gold extraction of 4 to 8 %.Various experimental results have indicated that a passivative film forms on the surface of some of the liberated gold. The selective destruction of the various minerals with oxidative acid leaches destroys and/or decomposes certain minerals which may form films on the gold surface by precipitation. The chemical composition of these films and precipitates depends on the mineralogy of the sample. These films may be oxides, sulphides, carbonates and cyanide complexes.The complexes can be destroyed, depending on the nature of the film, by interstage dilute acid and/or cyanide washes in an agitated vessel. The destruction of the films exposes the gold surface for cyanidation. Whereas most of the previous studies on the leaching of gold have focused on the whole ore, the emphasis in this study was on the leaching behaviour of gold from various ore constituents. This approach of studying the leaching behaviour of different gold bearing minerals has provided reasons why some ores leach better than others.     

含氰废水臭氧氧化处理试验研究

采用臭氧氧化法对某金矿氰化渣产生的含氰废水进行了试验研究。主要考察了在一定臭氧浓度条件下,氧化反应时间、反应pH、催化剂等因素对氰化物去除效果的影响,并确定了最佳反应条件。试验结果表明,采用臭氧对该含氰废水进行氧化处理,在pH=7.0、不添加催化剂,反应时间为75 min时,废水中游离CN~-最大去除率达96.3%,总CN~-最大去除率达92.3%。     

Cyanide oxidation by ozone in cyanidation tailings: Reaction kinetics

The treatment of cyanidation effluents is one of the main problems the gold mining industry faces. Different methods are available for the removal of cyanide but in most cases the consumption of reagents raises the cost to unaffordable levels, or there exists the formation of residual byproducts that are also toxic. Ozone gas is used in a new alternative approach that presents several advantages for oxidation of cyanide compounds. However, the lack of information on the reactions of cyanide compounds with ozone has limited its industrial application in cyanidation effluents.The oxidation of cyanide by ozone in aqueous solutions was studied using a bubble column reactor. The reactor was operated at different conditions of pH, ozone dosage rate, gas flow rate and cyanide concentration. Preliminary experiments were performed with synthetic cyanide solutions and the results :showed that the rate of cyanide oxidation may be described by an equation which is first order with respect to ozone concentration in the oxidizing gas, and zero order with respect to cyanide concentration in the aqueous solution. The rate constant obtained for the reaction was about 10⁻⁵ mol/L·s. The stoichiometry estimated for the reaction indicated one mole of cyanide reacts with one mole of ozone to form one mole of cyanate. These results were corroborated with industrial eff luents from two mines in Mexico.     

The cyanide leaching of gold in solutions containing sulfide

A large proportion of the gold processed in the 21^st century will be recovered from sulfide ores. Since the sulfide minerals are to some extent soluble in cyanide solutions, there will always be some sulfur species present in the leach solution. It has been shown that soluble sulfide hinders the rate of gold leaching, forming a protective layer of the type Au/S_x. Electrochemical studies of the constituent half reactions: gold oxidation; and oxygen reduction, were consistent with this view. The effect of sulfide and cyanide concentrations on the leaching reaction were investigated, and it was shown that the sulfur formed is chemically attacked by cyanide, resulting in higher leach rates at higher cyanide concentrations. The effect of lead was also studied and is discussed in detail.     

Mechanisms of sulfide ion oxidation during cyanidation. Part II: Surface catalysis by pyrite

The mechanisms and the reaction products for the oxidation of sulfide ions in the presence of pyrite have been established. When the leach solution contains free sulfide ions, oxidation occurs via electron transfer from the sulfide ion to dissolved oxygen on the pyrite mineral surface, with polysulfides being formed as an intermediate oxidation product. In the absence of cyanide, the polysulfides are further oxidised to thiosulfate, whilst with cyanide present, thiocyanate and sulfite are also formed from the reaction of polysulfides with cyanide and dissolved oxygen. Polysulfide chain length has been shown to affect the final reaction products of polysulfide oxidation by dissolved oxygen.The rate of pyrite catalysed sulfide ion oxidation was found to be slower in cyanide solutions compared to cyanide free solutions. Mixed potential measurements indicated that the reduction of oxygen at the pyrite surface is hindered in the presence of cyanide. The presence of sulfide ions was also found to activate the pyrite surface, increasing its rate of oxidation by oxygen. This effect was particularly evident in the presence of cyanide; in the presence of sulfide the increase in total sulfur from pyrite oxidation was 2.3 mM in 7 h, compared to an increase of <1 mM in the absence of sulfide over 24 h.     

难处理金矿热压氧化工艺研究

本试验以国内某超细微难处理金矿为研究对象,开展酸性热压氧化工艺研究;分析了温度因素对硫化矿物氧化、元素迁移和金氰化浸出等的影响。试验结果表明,通过温度变化可影响黄铁矿和砷黄铁矿氧化反应速率,进而对S、Fe和As元素的迁移状态产生影响。反应温度越高黄铁矿和砷黄铁矿氧化越彻底,有利于金的氰化浸出;完全氧化后金的浸出率约为94%。浮选金精矿中的黄铁矿、砷黄铁矿逐渐氧化转变为砷酸铁盐、铁砷硫硅等多元素共沉物质,未发现有碱式硫酸铁或铁矾物相,反应生成的各种沉淀产物对浸出率无显著影响。      

地沟油水解法基于浮选的再生技术研究*

本文选择食堂废弃的地沟油为研究对象,通过控制水解条件,获得不同性质的地沟油改性捕收剂。分别探究温度、催化剂、乳化剂用量等因素对地沟油水解的影响规律,确定其最佳的改性条件。采用接触角测定表征地沟油的改性效果,通过比较地沟油改性捕收剂在固废浮选方面的应用效果。结果表明地沟油改性剂具有一定的捕收作用,在浮选分离领域,可替代传统脂肪酸类捕收剂及非极性烃类捕收剂的使用。     

A kinetic and electrochemical study of the ammonia cyanide process for leaching gold in solutions containing copper

One of the biggest challenges for the gold industry in the 21st century is the presence of copper in gold containing ore bodies. This is because copper consumes large quantities of cyanide. In addition, copper cyanide species are more stable than free cyanide, and hence are problematic in events of tailings spillage. One of the methods which has been suggested for treating copper containing ores is to leach with an ammonia cyanide solution. The effect of copper and ammonia addition on gold leaching kinetics was studied in the present paper. It will be shown that when the solutions do not contain copper, the addition of ammonia decreases the rate of gold leaching. When copper is added to solution, the leach rate does decrease due to the formation of the copper cyanide complexes. However it will be shown that under conditions of zero free cyanide, gold does leach readily via the Cu(CN)₃²⁻ complex. It was found that the addition of ammonia had little effect on the leaching of gold by Cu(CN)₃²⁻, but did increase the leaching kinetics when the major cyanide species present is Cu(CN)₂⁻. Under these conditions, leaching in the absence of ammonia is very slow. The effect of copper(II) addition was also studied, and it was found that in the absence of free cyanide the presence of copper(II) increases the leach rate, provided there is enough ammonia to stabilise it against reaction with the copper(I) cyanide complexes.