【作者】 李海军；

【导师】 杨洪英；

【作者基本信息】 东北大学 ， 特殊冶金， 2016， 博士

【摘要】 钴是一种重要的战略金属,但我国钴资源紧张,多为共伴生矿。其中低品位钴矿石(次生氧化铜钴矿)是重要的钴伴生矿之一,其可选性差,有价金属品位低,难以回收利用。低品位钴矿石的嗜酸属细菌(Acidithiobacillus)生物浸出液存在固体蛋白颗粒和铁含量高的特点,造成溶剂萃取界面污染和钴电积产品劣质,难以采用传统的溶剂萃取—电积工艺流程回收其有价金属。本文针对上述低品位钴矿生物浸出液的特点,重点开展铜萃取界面污物的产生及消除工艺,固体颗粒絮凝脱除机理,针铁矿法除铁技术及其滤饼过滤性能研究,细菌蛋白对钴电积的影响及脱除机制,消除了生物浸出液固体蛋白颗粒,降低铁含量,最终实现铜钴的提取和分离,铜、钴回收率分别达到99.40%和99.03%。论文结果对我国低品位氧化铜钴矿的综合利用具有重要的意义,获得如下研究结果:(1)通过对铜萃取过程界面污物进行分离及鉴定,发现溶剂萃取时进入萃取界面的固体颗粒是影响乳液的稳定性、造成金属、萃取剂损失的主要原因。采用阴离子聚丙烯酰胺絮凝剂处理低品位钴矿浸出液,溶液去浊率可接近100%,使萃取界面污物的产生得以控制。(2)酸性硫酸盐介质中,引起界面污物产生的固体颗粒带有正电荷,具有良好的亲水特性。首次通过扩展德亚盖因—兰多—弗韦—奥弗比克理论(EDLVO理论)计算,确认颗粒之间的静电作用能及亲水排斥能是造成固体颗粒稳定,难于自然沉降的直接原因。研究发现,絮凝剂分子可通过异种电荷之间的静电作用包覆于颗粒表面,形成絮团,致使固体颗粒之间的亲水排斥能转化为疏水吸引能,以利于固体颗粒的沉降。(3)脱除固体颗粒后,钴矿浸出液被用于萃取提铜。采用有机相为25%LIX984N的煤油溶液,在萃取相比为1:1,平衡pH值为1.25的条件下,可使铜萃取率达99.40%,铁的夹带为4.03%,钻为0.85%。采用中性水对负载有机相洗涤,可有效降低铁和钴的共萃率。洗涤后的负载有机相采用200 g·L-1的硫酸水溶液进行反萃,在相比为1:1时,通过两级逆流反萃,铜反萃率可达98.10%。(4)针对限制溶剂萃取提钴的铁元素,采用部分水解针铁矿法(E.Z法)进行脱除,并对沉淀的滤饼过滤性能进行研究。首次通过中心复合设计试验,建立了除铁过程控制模型并获得了除铁参数的优化方法。E.Z法除铁后,含钴溶液的除铁率及钴回收率可同时接近100%,并且铁渣中铁含量及硫酸根含量分别控制在60%以上及10%以下。温度、pH值及晶种用量均会对构成沉淀的物质种类及形貌,过滤时的滤液流量及滤液质量产生影响。首次证实了针铁矿滤饼滤孔轮廓的分形维数与沉淀颗粒的物质种类及生成条件相关性。当滤饼中孔隙的分形维数介于1.24～1.25之间时,过滤过程能够维持较好的滤液流量及滤液质量。(5)采用溶剂萃取技术,对影响电积过程的低浓度铜、铁元素进行脱除,并对钴进行富集沉淀。最终形成的富钴溶液,钴浓度可达37.420 g·L-1,铁浓度为0.875 mg·L-1,铜浓度为0.178 mg·L-1,细菌蛋白为0.152 mg·L-1。此电解液采用氢氧化钠沉降,制备电积用氢氧化亚钴粉末,钴沉淀率可接近完全。(6)针对生物冶金技术回收电积钴时易产生劣质产品的问题进行研究。首次发现磷酸类萃取剂P507及含钴电解质对生物蛋白表现出良好润湿性能,致使部分细菌及其降解产物随钴的溶剂萃取进入电积流程。钴电积时,细菌蛋白吸附于阴极表面,增加钴析出的阴极过电位及沉积能耗,削弱整平剂的作用。当电解液内细菌蛋白浓度高于30 mg·L-1时,阴极钴形貌发生改变,甚至开裂剥落。(7)对钴电积过程进行优化,适宜电积条件为钴浓度60 g·L-1,硫酸钠浓度为25 g·L-1,电解质溶液温度为60 ℃,电解液pH值维持在4.0～5.0之间,阴极电流密度为400 A·m-2,该条件下钴电积电流效率可达到98%以上。研究中发现细菌蛋白存在累积现象,但累积的细菌蛋白可以通过提高阴极电流密度的方法予以分解。更多还原

【Abstract】 Cobalt is an important strategic metal,but cobalt resources are scarce,mostly associated with the ore in our country.The low grade cobalt ore(secondary copper cobalt oxide ore)is important one of the cobalt associated ore,which has poor separability.The valuable metals are low grade and difficult to recycle.The leaching solution obtained that is produced through bioleaching the low grade cobalt ore is the bioaerosol characterized by great contents of Fe and solid particles,which can leads to the loss in metals and extractant and result in the products with poor quality.As a result it is difficult to recyce the valuable metals by the traditional solvent-extraction process.Aiming at biological leaching liquid characteristics of the low grade cobalt ore,this paper carried out the formation and removal of interfacial cruds formed in the extraction of copper(Cu),the investigation of the removal of soil particles using flocculation,the analysis of Fe removal by using goethite process and its cake filtration performances and the mechanism of the influence for bacterial protein on the Co extraction based on electrowinning process to eliminate solid protein particles of the biological leaching liquid,reducing iron content.In the end,copper and cobalt are extracted and separated,and the recovery rate of copper and cobalt is 99.40%and 99.03%separately.Results of the papers have the vital significance to the comprehensive utilization of low grade copper oxide cobalt in our country,and obtain the following results:(1)By conducting separation and recognition on the interfacial cruds formed in the process of extracting Cu,it was found that solid particles which enter into the interface when solvent extraction were main reasons leading to interfacial cruds,the loss in metals and extractant.Anionic polyacrylamide flocculant was used to treat the bioleaching liquor of LGCO.The results showed that rate of removing turbidity in the solution reached to 100%,and the produce of cruds in extraction interfaces can be controlled.(2)The solid particles in sulfuric acid media,which resulted in the interfacial cruds,were shown to carry positive charges,and had good hydrophilic properties.The results calculated using EDLVO theory firstly confirmed that the electrostatic interaction and hydrophilic repulsive free energy(HPFE)among the particles were the main reason leading to the stability of solid particles which further causing the difficulty in natural sedimentation.The study found that the flocculant molecules can form floc formation which can be coated on the surface of the particles by electrostatic interaction between dissimilar charges.And then the hydrophilic repulsion energy between the solid particles can be transformed into hydrophobic attracting energy,which facilitates the settling of solid particles.(3)The bioleaching solution of cobalt ore was utilized to extract Cu after the removal of solid particles.The extraction rate of Cu could live up to 99.40%on the conditions including the kerosene solution with the organic phase of 25%LIX984N,a phase ratio of 1:1 and pH of 1.25.Besides,the entrainment of Fe was 4.03%;while the entrainment of Co was merely 0.85%.Through washing the loaded organic phases(LOP)using neutral water the total iron and cobalt extraction rate can be effectively reduced.The washed LOP were conducted reverse extraction using sulfuric acid solutions of 200 g·L-1.In the case of a phase ratio of 1:1,the reversion extraction rate of Cu using multi-stage counter-current extraction could reach 98.10%.(4)The article uses E.Z goethite process to remove Fe limiting extracting cobalt from solvent extraction,and then study filtration performance of filter cakes.In this work,firstly based on the central composite design experiment,the authors constructed a model of controlling the process of Fe removal and proposed a method of optimizing the parameters of Fe removal using E.Z goethite process.By removing Fe using E.Z goethite process,both Fe removal rate and the recovery rate of Co in the solution containing Co were nearly 100%.Moreover,the contents of Fe and sulphate in Fe slag were controlled to be greater than 60%,and smaller than 10%,respectively.Temperature,pH,and the addition amount of crystal seeds all might influence the types,and morphologies of precipitated matters,as well as the flux and quality of the filtrate in the case of filtration.The correlation between fractal dimension of the morphology for the pores in a filter cake and the matter types and formation conditions of precipitated particles was confirmed firstly.The fractal dimension of the pores ranging between 1.24 and 1.25 was able to maintain the preferable flux and quality of the filtrate.(5)Using solvent extraction technique to remove low concentrations of Fe and Cu which effects the electrolysis process,and then enrich Co,in the end cobalt-rich solution can be got.The concentration of Co is 37.420 g·L-1,the concentrations of Fe and Cu are 0.875 mg·L-1 and 0.178 mg·L-1 respectively,while the concentration of bacterial protein is 0.152 mg·L-1.This electrolyte adopted the precipitation of NaOH to prepare the Co hydroxide powder for the use in electrowinning process;the precipitation rate of Co could reach 100%.(6)Biological metallurgy technology recovering electro winning cobalt is easy to produce inferior products.This work studies the problem.Phosphorous extractant P507 and the electrolyte containing Co exhibited good wettability,which made some bacteria and their degradation products evolving into the electrowinning process along with the solvent extraction of Co.When conducting electrowinning process of Co,the bacteria protein was found to be adsorbed on cathode surface,which increased the cathodic overpotential and the energy consumption of the precipitated Co to further weaken the function of leveling agent.As the concentration of the bacteria protein in the electrolyte was higher than 30 mg·L-1,the morphology of cathodic Co presented change and even exhibited cracking and spalling.The concentration of bacteria protein in this research was significantly smaller than 30 mg·L-1.(7)The electrowinning process of Co was optimized,and the current efficiency could reach more than 98%.The optimal conditions included Co concentration of 60 g·L-1,sodium sulfate concentration of 25 g·L-1,the temperature of 60 ℃ and pH values ranging from 4.0 to 5.0 for electrolyte solution,as well as cathode current density of 400 A·m-2.Accumulated bacteria proteins were also found in this research,which could be decomposed by increasing cathodic current density.更多还原