氯化焙烧铜熔炼渣的过程机理及动力学

提出一种以CaCl_(2)为氯化剂,采用氯化焙烧法从铜熔炼渣中高效回收锌的工艺。利用热力学计算、热重–差热(TG-DSC)分析和X射线衍射(XRD)等手段,研究氯化反应机理和氯化焙烧过程动力学。结果表明,CaCl_(2)氧化分解和所有含锌相的氯化反应温度均分别高于774.3和825℃。铜熔炼渣的氯化焙烧过程可分为4个阶段,依次为吸附水脱除、结晶水脱除、含铁相氧化和锌的氯化挥发。铁氧化阶段和锌氯化挥发阶段的表观活化能分别为101.70和84.4 k J/mol,铁氧化过程的最概然机理函数为Avrami–Erofeev方程(n=2),锌氯化过程符合未反应核收缩模型且受化学反应控制。

锑火法冶炼过程锑、砷物质流分析

应用物质流分析于锑火法冶炼系统。以锑、砷为目标元素,建立基于生产系统的物质平衡表和物质流图,构建有关系统直接回收率、废物回收率、资源效率的评价指标体系。结果表明:锑的资源效率为89.21%,挥发熔炼、还原熔炼和除杂精炼过程锑的直收率分别为78.79%、91.00%和96.06%。同时,每产出1 t金属锑,会有11.94 kg的砷进入到冶炼系统中。砷为冶炼过程主要杂质元素。重点分析砷在主要单元过程中的分布转化行为。基于物质流分析提出提高锑资源利用效率和清洁生产的建议。

硫化还原法协同回收铜冶炼渣中的铜、铅和锌

采用硫化还原法从铜冶炼渣中协同回收铜、铅和锌。以黄铁矿为硫化剂,在还原气氛下选择性硫化回收渣中有价金属。通过热力学分析和实验,确定该工艺的可行性和可靠性。确定了最佳的实验条件:硫化剂黄铁矿添加量为铜冶炼渣质量的26%,焦炭添加量为铜冶炼渣总质量的6%,温度1350℃,熔炼时间3h。在优化条件下,铜、铅和锌回收率分别为97.58%、89.91%和98.20%。清洁渣中铜、铅和锌含量分别为0.10%、0.01%和0.38%。铜锍相含铜7.28%,锌在气相、渣相和铜锍相中的分布比例分别为80.93%、10.09%和8.98%,铅在气相、渣相和铜锍相的分布比例分别为40.12%、1.79%和58.09%。铜锍相主要由Cu_(8)S_(5)、FeS和Cu、Pb、Fe等金属组成,渣中Fe_(3)O_(4)含量由19.50%降至2.97%。

熔渣中金属液滴沉降过程流体力学模拟

建立熔炼渣中金属液滴沉降过程的数学模型,研究不同粘性模型下金属/熔渣界面张力对液滴沉降速度以及拖曳力的影响。结果表明:对于较小直径的液滴,Laminar模型和RNG k-ε湍流模型能够准确预测液滴最终沉降速度;界面张力对液滴沉降速度有影响,且影响作用随着液滴尺寸增大而逐渐增大;“RNG+CSS”模型可以准确描述液滴沉降过程和液滴沉降速度的变化。结合数学模型和实验数据,推导出耦合界面张力作用下拖曳力系数计算公式。该模型揭示熔炼渣中金属液滴沉降过程机理,为实际生产中降低渣中有价金属含量提供理论指导。

铜复杂资源造锍熔炼过程中MgO对铜锍和二氧化硅饱和铁硅渣相平衡的影响

采用高温平衡实验及电子探针微区分析方法研究铜复杂资源中MgO对造锍熔炼平衡体系铜锍及熔炼渣成分(FeO_(x)-SiO_(2)-MgO)的影响。结果表明,在1300℃、p(SO_(2))=10kPa熔炼条件下,增加熔炼渣中MgO含量可降低渣中FeO的活度,进而降低渣中氧分压(p(O_(2)))、减少铜在渣中化学溶解损失量;同时,渣中FeO活度降低可促进铜锍中FeS氧化进渣,提高铜锍品位。在高硅渣型中,过量MgO易在渣中形成固相夹杂颗粒(Mg_(2)SiO_(4)-Fe_(2)SiO_(4)),导致渣黏度升高、增加渣中铜损失。当熔炼温度由1200℃升至1300℃及p(O_(2))为10-6kPa时,FeO_(x)-SiO_(2)-MgO渣中MgO的最大溶解量由3%增至8%(质量分数);渣中MgO含量增加时,可通过添加SiO_(2)熔剂调整渣型、升高熔炼温度,进而降低渣中固相析出物含量,改善熔渣性质。

Copper smelting mechanism in oxygen bottom-blown furnace

The SKS furnace is a horizontal cylindrical reactor similar to a Noranda furnace,however,the oxygen enriched air isblown into the furnace from the bottom.Mechanism model of the SKS process was developed by analyzing the smeltingcharacteristics deeply.In our model,the furnace section from top to bottom is divided into seven functional layers,i.e.,gas layer,mineral decomposition transitioning layer,slag layer,slag formation transitioning layer,matte formation transitioning layer,weakoxidizing layer and strong oxidizing layer.The furnace along the length direction is divided into three functional regions,that is,reaction region,separation transitioning region and liquid phase separation and settling region.These layers or regions play differentroles in the model in describing the mechanism of the smelting process.The SKS smelting is at a multiphase non-steady equilibriumstate,and the oxygen and sulfur potentials change gradually in the length and cross directions.The smelting capacity of the SKSprocess could be raised through reasonably controlling the potential values in different layers and regions.

Relationship between copper content of slag and matte in the SKS copper smelting process

In the newly developed oxygen-enriched bottom-blowing copper smelting process(also known as the SKS copper smelting process), Cu loss in slag is one of the most concerning issues. This paper presents our research results concerning the relationship between the Cu content of the matte and slag in the SKS process; the results are based on actual industrial production in the Dongying Fangyuan copper smelter. The results show that the matte grade strongly influences Cu losses in slag. The dissolved and entrained losses account for 10%–20% and 80%–90% of the total SKS industrial Cu losses in slag, respectively. With increasing matte grade, the dissolved and entrained Cu losses in the SKS slag both increase continuously. When the matte grade is greater than 68%, the content of Cu in the smelting slag increases much more dramatically. To obtain a high direct recovery of copper, the matte grade should be less than 75% in industrial SKS copper production.

Multiphase equilibrium modeling of oxygen bottom-blown copper smelting process

A computational thermodynamics model for the oxygen bottom-blown copper smelting process(Shuikoushan,SKS process)was established,based on the SKS smelting characteristics and theory of Gibbs free energy minimization.The calculated results of the model show that,under the given stable production condition,the contents of Cu,Fe and S in matte are71.08%,7.15%and17.51%,and the contents of Fe,SiO2and Cu in slag are42.17%,25.05%and3.16%.The calculated fractional distributions of minor elements among gas,slag and matte phases are As82.69%,11.22%,6.09%,Sb16.57%,70.63%,12.80%,Bi68.93%,11.30%,19.77%,Pb19.70%,24.75%,55.55%and Zn17.94%,64.28%,17.79%,respectively.The calculated results of the multiphase equilibrium model agree well with the actual industrial production data,indicating that the credibility of the model is validated.Therefore,the model could be used to monitor and optimize the industrial operations of SKS process.

Thermodynamic analysis and process optimization of zinc and lead recovery from copper smelting slag with chlorination roasting

An efficient chlorination roasting process for recovering zinc(Zn)and lead(Pb)from copper smelting slag was proposed.Thermodynamic models were established,illustrating that Zn and Pb in copper smelting slag can be efficiently recycled during the chlorination roasting process.By decreasing the partial pressure of the gaseous products,chlorination was promoted.The Box−Behnken design was applied to assessing the interactive effects of the process variables and optimizing the chlorination roasting process.CaCl_(2) dosage and roasting temperature and time were used as variables,and metal recovery efficiencies were used as responses.When the roasting temperature was 1172℃ with a CaCl_(2) addition amount of 30 wt.%and a roasting time of 100 min,the predicted optimal recovery efficiencies of Zn and Pb were 87.85%and 99.26%,respectively,and the results were validated by experiments under the same conditions.The residual Zn-and Pb-containing phases in the roasting slags were ZnFe_(2)O_(4),Zn_(2)SiO_(4),and PbS.

Copper and arsenic substance flow analysis of pyrometallurgical process for copper production

The metabolism of copper and arsenic in a copper pyrometallurgy process was studied through substance flow analysis method.The mass balance accounts and substance flow charts of copper and arsenic were established,indicators including direct recovery,waste recycle ratio,and resource efficiency were used to evaluate the metabolism efficiency of the system.The results showed that,the resource efficiency of copper was 97.58%,the direct recovery of copper in smelting,converting,and refining processes was 91.96%,97.13%and 99.47%,respectively.Meanwhile,for producing 1 t of copper,10 kg of arsenic was carried into the system,with the generation of 1.07 kg of arsenic in flotation tailing,8.50 kg of arsenic in arsenic waste residue,and 0.05 kg of arsenic in waste water.The distribution and transformation behaviors of arsenic in the smelting,converting,and refining processes were also analyzed,and some recommendations for improving copper resource efficiency and pollution control were proposed based on substance flow analysis.

Thermodynamic modeling of antimony removal from complex resources in copper smelting process

This work investigated the reaction mechanism of Sb in copper smelting process. The difference of multi-phase distribution of Sb in four typical copper smelting processes was analyzed. A multi-phase equilibrium model of the oxygen-enriched bottom-blow copper smelting process was developed. The impacts of Cu, S, and Sb concentrations in raw materials on Sb distribution in multiphases were researched. This model was also used to investigate the effect of process factors such as copper matte grade, oxygen-enriched concentration, smelting temperature, and oxygen/ore ratio(ratio of oxygen flow rate under standard conditions to concentrate charge rate) on Sb distribution behavior. The results showed that calculation data were in good agreement with the actual production results and literature data. Increasing the Cu content and decreasing the S and Sb contents in the concentrate, increasing the copper matte grade, oxygen/enriched concentration, and oxygen-ore ratio, and at the same time appropriately reducing the smelting temperature are conducive to the targeted enrichment of Sb into the slag. Modeling results can provide theoretical guidance for the clean and efficient treatment of complex resources and the comprehensive recycling of associated elements.

Physicochemical and environmental characteristics of alkali leaching residue of wolframite and process for valuable metals recovery

Physicochemical and mineralogical characteristics of an alkali leaching residue of wolframite were studied by XRD,SEM−EDS,chemical phase analysis,mineral liberation analyzer(MLA),and TG−DSC methods.Batch leaching tests,toxicity characteristic leaching procedure(TCLP)tests and Chinese standard leaching tests(CSLT)were conducted to determine the environmental mobility of toxic elements.The results show that,due to the high contents of W,Fe,Mn,Sn,and Nb,the residue is with high resource value,but the content of a toxic element,As,is also high.The existing minerals of the investigated elements mainly occur as monomer particles,but it is difficult to extract these valuable metals by conventional acid leaching due to their mineral properties.The release of As increases over time in acidic environment.The leaching concentration of all investigated harmful elements through TCLP is within the limiting value,while the leaching concentration of As through CSLT exceeds the limiting value by more than 4 times,so the residue is classified as hazardous solid waste based on the Chinese standard.A process for valuable metals recovery from this residue was proposed.Preliminary experimental results indicated that the main valuable metals could be extracted effectively.

Tungsten and arsenic substance flow analysis of a hydrometallurgical process for tungsten extracting from wolframite

In this study,the metabolism of a hydrometallurgical process for tungsten extracting from wolframite was studied through substance flow analysis.The mass balance accounts,substance flow charts of tungsten and arsenic were established to evaluate the metabolism efficiency of the investigated system.The results showed that,the total tungsten resource efficiency of the system was 97.56%,and the tungsten recovery of unit process autoclaved alkali leaching,ion exchange,Mo removing,concentration and crystallization was 98.16%,98.94%,99.71%,99.89%,respectively.Meanwhile,for extracting 1 ton of tungsten into the qualified ammonium paratungstate,10.0414 kg of arsenic was carried into the system,with the generation of 7.2801 kg of arsenic in alkali leaching residue,1.5067 kg of tungsten in arsenic waste residue,and 1.2312 kg of tungsten in Mo residue.Besides,7.9 g of arsenic was discharged into nature environment with waste water,15.5 g of arsenic was entrained into the final APT.The distribution and transformation behaviors of arsenic during production were analyzed through phases change analysis,and some recommendations for improving the resource efficiency of tungsten and pollution control during production were also proposed based on the substance flow analysis in this study.