辉钼矿湿法冶金新工艺及其机理研究_图文

1、分类号VDC博士学位论文 辉钼矿湿法冶金新工艺及密级其机l 73S 259理研究The research on novel hydrometallurgy for molybdenite concentrate and its mechanisms作者姓名:曹占芳学科专业:化学工艺学院(系、所:化学化工学院指导教师:钟宏教授答辩委员会主席地中 南大学2010年5月”.、:一:、 .1o原创性声明本人声明,所呈交的学位论文是本人在导师指导下进行的研究 工作及取得的研究成果。尽我所知,除了论文中特另tl;Dl:l以标注和致谢 的地方外,论文中不包含其他人已经发表或撰写过的研究成果,也不 包含为获得

2、中南大学或其他单位的学位或证书而使用过的材料。与我 共同工作的同志对本研究所作的贡献均已在论文中作了明确的说明。作者签名:j嶂 日期:扯年土月立日 学位论文版权使用授权书本人了解中南大学有关保留、使用学位论文的规定,即:学校 有权保留学位论文并根据国家或湖南省有关部门规定送交学位论文, 允许学位论文被查阅和借阅;学校可以公布学位论文的全部或部分内 容,可以采用复印、缩印或其它手段保存学位论文。同时授权中国科 学技术信息研究所将本学位论文收录到中国学位论文全文数据库, 并通过网络向社会公众提供信息服务。期a盟翌年月受日 博士学位论文 摘要 摘要针对现有辉钼矿焙烧工艺污染严重,且难以实现钼及伴生金

3、属高 效经济回收的弊端,进行了辉钼矿常温常压湿法浸出和浸出液中钼、 铼的分离富集及其机理的研究,为发展环境友好的钼湿法冶金新工艺 提供理论基础。基于含氧氯酸盐在溶液中具有高的电极电位,表现出很强氧化能 力的特性,对氯酸钠和次氯酸钠氧化分解辉钼矿、黄铜矿等进行热力 学计算。结果表明,氯酸钠、次氯酸钠氧化分解辉钼矿、黄铜矿等过 程的G0值均为负值,且绝对值较大,说明氯酸纳、次氯酸钠都能 应用于对辉钼矿的氧化分解。研究了氯酸钠氧化分解辉钼矿的行为与规律,发明了一种使用电 解氯化钠盐水生成的氯酸钠电解液为氧化剂、在酸性水溶液条件下高 效氧化分解辉钼矿精矿的新方法。以氯酸钠为氧化剂,在 C(NaCl=0

4、.71mol/L,C(H2S04=73.3L,NaCl03/MoS2=3.6(mol/m01, L/S=30,T=70,搅拌速率为400r/min,t-6h的条件下,钼的浸 出率为98.62%,铼的浸出率为99.52%,铜的浸出率为99.77%,铁的 浸出率为99.28%,实现了多种硫化矿物的全分解。在对氯酸钠氧化 分解辉钼矿研究的基础上,将电化学合成的氯酸钠电解液,不经净化、 结晶等操作,调整酸度后直接用来浸出辉钼矿。优化确定采用的氯酸 钠电解合成工艺条件为:槽电压3.O V,电流密度653.2A/m2,搅拌 速度100r/min,Na2Cr207浓度3g/L,pH=6.7,温度75,电解时

5、 间35h,此时电解液含氯酸钠290.90g/L,含次氯酸钠7.08g/L,钼、 铼浸出率分别为98.51%和99.56%。采用氯酸钠电解液湿法氧化分解 辉钼矿的方法具有氧化剂生产成本低、使用安全等优点。浸出动力学 研究表明浸出过程符合收缩核模型,表观活化能Ea=104.6kJ/mol,过 程受化学反应控制。氯化钠浓度4mol/L,碳酸钠6g/L,碳酸氢铵5g/L,缓冲体系pH=8.59.5, 室温的条件下,电解240min时钼浸出率可达99.35%,铼浸出率为 99.79%,电流效率为62.75而非缓冲体系电氧化工艺达到同样钼浸 出率时电流效率仅为40.44%。通过缓冲体系的应用,使钼精矿中

6、钼、 铼选择性高效氧化浸出,而黄铜矿基本不浸出,浸出渣中铜含量为 10.84%,回收率达到97.93%。缓冲体系中电氧化工艺是一种更为高效 环保的辉钼矿选择性电氧化分解工艺。该工艺特别适用于德兴铜矿高 铜钼精矿的的湿法分解。通过对电氧化过程阳极氧化、氧化剂变化规律的研究,建立了电 氧化浸出过程的动力学模型,揭示了缓冲体系中电氧化分解辉钼矿的 浸出机理。结果表明,辉钼矿在阳极上不能直接被氧化,NaCl介质 中析氯反应起了主导作用,辉钼矿的氧化浸出主要是借助于阳极析出 的氯气转化生成的氧化剂,氧化剂主要成分是NaCl0。浸出动力学 研究表明,pH=9的碳酸盐一酸式碳酸盐缓冲体系中,辉钼矿的浸出表

7、观活化能E=8.56kJ/mol,过程受固膜扩散控制。采用溶剂萃取技术对辉钼矿浸出液中的Mo(VI、Re(VII进行了萃 取与反萃研究,建立了萃取反应模型方程,揭示了萃取剂N235对钼、 铼金属离子的萃取机理。在优化的萃取条件下,氯酸钠电解液浸出辉 钼矿溶液经3级萃取后,Mo(VI、Re(VII的萃取率分别达到99.84%和95.19%;采用17%的氨水为反萃剂,在优化的反萃条件下,3级 反萃后Mo(VI、Re(VII的反萃率分别达到99.90%和99.73%。在优 化的萃取条件下,电氧化分解辉钼矿浸出液经3级萃取后,Mo(VI、 Re(VII的萃取率分别达到99.77%和94.73%;采用1

8、7%的氨水为反萃 剂,在优化的反萃条件下,3级反萃后Mo(VI、Re(VII的反萃率分 别达到99.89%和99.54%。等摩尔法实验和红外光谱分析表明,N235萃取Mo(VI、Re(VII离子时,叔胺基与溶液中的离子发生了配位反 应,分别以(R3NH2(M0022(S043an RaNHRe04形式进行萃取。 采用D201树脂对反萃液中的Mo(VI、Re(VII吸附分离性能进 行了考察,建立了树脂吸附动力学和热力学模型,揭示了阴离子交换 树脂对Mo(VI、Re(VII的吸附机理。静态吸附实验表明,D201树脂 对Mo(VI、Re(VII的吸附容量都随吸附时间和金属离子初始浓度的 增加而增大。

9、静态分离实验表明,树脂对溶液中的Re(VII具有良好 的吸附选择性,溶液中Mo(VI初始浓度越大分离因子越高。对氯酸 钠浸出体系反萃液,在吸附温度30,pH=8,吸附时间l h条件下,IIRe(VII、Mo(VI吸附率分别为92.4l%、3.19%,分离因子为190.49; 对电氧化浸出体系反萃液,在吸附温度30,pH=8,吸附时间1h 条件下,Re(VII、Mo(VI吸附率分别为92.18%、3.46%,分离因子 为169.56。实验数据符合Boyd液膜扩散方程,树脂对Mo(VI、Re(VII 的吸附过程属于液膜扩散控制过程。吸附过程为单分子层吸附,符合 Langmuir和Freundlic

10、h等温吸附模型,根据拟合结果计算得到的D201树脂对Mo(VI、Re(VII的饱和吸附容量分别为4.2633mmol/g、4.2355 mmol/g。全流程技术经济分析表明,与传统焙烧工艺相比,缓冲体系电氧 化浸出工艺是一种高效环保的辉钼矿湿法分解工艺。对于德兴铜矿的 辉钼精矿,钼回收率达到99.04%,铼回收率达到85.84%,铜回收率 超过97%,年净增经济效益2000多万元,减排S022681t/年,具有 明显的经济效益和环境效益。关键词辉钼矿,湿法浸出,氧化分解,萃取,吸附III 博+学位论文AB STRACTThe roasting method gradually shows it

11、s shortcomings.During roasting,many valuable metals are lost due to volatilization and the S02 generated is a source of environmental pollution.The novel cold atmospheric leaching of molybdenite,the process of extraction and separation of molybdenum and rhenium in the extract,and their mechanism hav

12、e been investigated,providing theoretical basis for environment-friendly hydrometallurgy of molybdenite.Chlorate and hypochlorite in solution have high electrode potential and strong oxidative property.Thermodynamic calculations of the oxygenolysis process of molybdenite by sodium chlorate and sodiu

13、m hypochlorite were carried out.The results showed that valuesofG。 were negative and the absolute values of them were high if sodium chlorate and sodium hypochlorite were used as oxidant in the molybdenite leaching process.In the view of thermodynamic point,MoS2, CuFeS2,FeS2and ReS2etc.could be leac

14、hed by acidic chlorate system and alkaline sodium hypochlorite system theoretically.In this paper,the technology of molybdenum extraction from molybdenite concentrate by using sodium chlorate has been investigated, and a novel hydrometallurgical extraction technology of molybdenite by using sodium c

15、hlorate electrolyte was introduced.The optimized leaching conditions are as followed:C(NaCl=0.71mol/L,C(H2S04=73.3g/L, NaCl03/M082=3.6(mol/m01,L/S=30,T=70,stirring rate is 400 r/min,t-6h.Under these conditions,leaching yield of molybdenum is 98.62%,leaching yield of copper is 99.77%,leaching yield o

16、f iron is 99.28%,leaching yield of rhenium,99.52%;while leaching of molybdenite is completed,Cu,Fe,Re were almost completely leached into the liquid.The acidic sodium chlorate electrolyte by electrochemical synthesis,without purification,crystallization,but just adjust the acidity and was directly u

17、sed for leaching of molybdenite.The optimized electrosynthesis conditions of sodium chlorate are as followed:cell voltage of 3.0V current density of 653.2A/mz,stirring rate of 100r/min, IV博士学位论文concentration of potassium dichromate of 3g/L.pH=6.7,75,35h. Under this electrosynthesis conditions,sodium

18、 chlorate iS 290.90vet.。 sodium hypochlorite is 7.08L,leaching yield of molybdenum is 98.51%.and leaching yield of rhenium iS 99.56%.It was an efficient and economic wet leaching process that sodium chlorate electrolyte was used for leaching molybdenite,and it can also reduce cost largely.The kineti

19、c study showed that the process of leaching molybdenite using acid sodium chlorate system is represented by shrinking core model,the apparentleaching process.Anode oxidation and oxidant have been investigated.and dynamic model of leaching process was established.The results showed thatmolybdenite co

20、uldnt be electro.oxidated at the anode directly in the bu虢r system.The chlorine evolution reaction hasplayed a dominant role V博士学位论文in sodium chloride medium.Sodium hypochlorite iS the main oxidant of oxidation leaching,which transformed from chloration liberated at the anode.The kinetic study showe

21、d that a shrinking core model is presented to describe the dissolution and to analyze the data.It was established that the leaching process is mainly controlled by diffusion through a porous product layerthe apparent activation energy of this dissolution process was found to be 8.56kJ/m01.The studie

22、s on extraction of Mo(VI,Re(VIIin the solution and its mechani sm by using N235extractant have been investigated.For extract solution of sodium chlorate,the percentage extraction rates of Mo(VI and Re(VIIunder the optimized extraction conditions were about 99.84%and 95.19%;Stripping of molybdenum to

23、 aqueous phase was efficient when 17%ammonia liquor were applied,the Mo(VIand Re(VIIstripping efficiencies under the optimized stripping conditions were about 99.90%and 99.73%.For electric-oxidation extract solution, the percentage extraction rates of Mo(VIand Re(VIIunder the optimized extraction co

24、nditions were about 99.77%and 94.73%; Stripping of molybdenum to aqueous phase was efficient when 17% ammonia liquor were applied,the Mo(VIand Re(VIIstripping efficiencies under the optimized stripping conditions were about 99.89% and 99.54%.The results of equimolar seriers method and infrared spect

25、ral analysis indicates that the coordinate reactions in aqueous solution happened while N235extracted Mo(VIand Re(VIIions, (R3NH2(M0022(S043and R3NHRe04come into being,respectively。 The adsorption and separation capability for Mo(VIand Re(VII ions of D201resin have been investigated,adsorption kinet

26、ics and thermodynamics were revealed by analyzing adsorption data.The results showed that the adsorption capacity of D201for Mo(VIand Re(VII ions increases with increase in adsorbing time and the initial ions concentration.For dualistic mixed solution of Mo(VIand Re(VII,the separation capability of

27、D201for Re(VIIand Mo(VIhas been investigated,it indicates that D201has excellent adsorption selection for Re(VIIions,and satisfy the separation demands.For stripping solution of sodium chlorate system,the adsorption rate of Re(VIIand Mo(VIareVl博士学位论文 ABSTRACT92.4l%,3.19%,respectively,and separating

28、factor is 190.49,when adsorption condition is 30,pH=8,and absorbing time 1h;For stripping solution of electric-oxidation system,the adsorption rate of Re(VIIand Mo(VIare 92.18%,3.46%,respectively,and separating factor is 169.56,when adsorption condition is 30,pH=8,and absorbing time 1h.The experimen

29、tal data fit BoydS diffuse equation of liquid film,indicating that the adsorption is controlled by liquid film diffuse;the isothermal adsorption obeys Langmuir and Freundlich equation,especially the former equation.The saturated adsorption capacity of D201for Mo(VIand Re(VIIcalculated base on simula

30、ted results were 4.2633mmol/g,4.2355mmol/g,respectively.The results of rough cost and economic analysis for molybdenite of Dexing CopperMine showed that,compared to conventional roasting process,the overall yield of molybdenum is 99.04%,the overall yield of rhenium is 85.84%,increase the recovery fo

31、r rhenium by 25%,and more than 97%copper can be recovered,The newincreased income is over 2000million yuan per annum,the reduced quality of S02is 2681t per annllm.KEY WORDS molybdenite,hydrometallurgy,oxygenolysis,extraction, separationVlI博士学位论文 目录 目 录博士学位论文 目录博士学位论文 目录博士学位论文 目录博士学位论文 目录V博士学位论文 目录1.

32、1引言第一章绪论钼是一种稀有难熔金属,在元素周期表中属于第六副族,1778年瑞典化学 家用硝酸分解辉钼矿发现了元素钼,并首次分离出钼酸和制取了若干种钼酸盐。 金属钼具有高强度、高熔点、耐腐蚀、耐磨研等优剧2硼。工业上以二硫化钼、 钼酸盐、金属钼、低合金钼基材料以及高合金钢的形式广泛用于各部门,如机械、 汽车、航天、航空、宇宙开发、石油化工、食品、防腐、塑料、复合材料、真空 工程、化工、电气和电子技术、冶金机械、医药、农业等【71。目前己知的钼矿物大约有20多种,但其中具有工业应用价值的仅有四种, 即辉钼矿(MoS2、钼酸钙矿(CaM004,钼酸铁矿(Fe2033M003-7H20和钼酸铅矿 (

33、PbM004。所有钼矿物中,辉钼矿的工业价值为最高,分布最广,约有99%的 钼呈辉钼矿的形式存在,占世界开采量的90%以上。辉钼矿是钼最主要的矿石 来源,它是一种质软并带有金属光泽的铅灰色矿物,外观与石墨相似,呈鳞片状 或薄板状的晶体,具有层状六角型晶格,图1.1为其结构示意图【3】。辉钼矿是已 知含铼(Re最高的矿物。铼与钼的离子半径相近,故铼经常置换钼而富集于 辉钼矿中,成为铼的主要工业来源。铼主要从钼精矿的氧化焙烧烟气淋洗液或湿 法浸出液中进行回收,通过萃取法或离子交换法制成高铼酸钾或高铼酸铵,经还 原法得到金属铼粉【8】。铼是银灰色的金属,熔点高达3180,在金属中仅次于 钨,居第二位

34、。铼非常硬、耐腐蚀、耐磨且有良好的延展性。特别是由于其呈密 排的六方晶体结构,可在低温下保持它的硬度和延展性且在高温和温度骤变情况 下保持高的强度和良好的抗蠕变性能f9J。9I 一Il 一国k。 滋夸l I 1Ll.一I:=;一涔泌厂r 丽 一 I、,I图1-1辉钼矿的结构焙烧一氨浸工艺是钼的经典冶金工艺,焙烧使辉钼矿中Mo氧化转变成为氨 溶性的M003,20世纪70年代之前世界上几乎90%纯钼化合物的生产都是采用该 类工艺【lo】。无论是经典的焙烧氧化工艺还是改进的焙烧氧化工艺,以及近年来 发展起来的新的钼冶金工艺都存在流程长、原料消耗高、金属回收率低、环境污 染严重及许多贵金属难回收或回收

35、率极低等缺点。20世纪70年代以来,国内外竟 相开展了辉钼矿全湿法新工艺的研究,其核心是在矿浆状态下将辉钼矿氧化转化 成为钼的氧化物或其盐,其优势在于能处理各种品位的钼矿物,适应性广,避免 了焙烧工序从而有效解决ys02气体的环境污染问题【12卅71。钼矿物经湿法分解后 可通过溶剂萃取或离子交换等新型分离技术回收,缩短了工艺流程,同时也能高 效综合回收多种伴生有价金属,如铼等11。全湿法分解工艺将成为一种环境友 好的辉钼矿主要冶金方法【1823j。本课题来源于“十一五”国家科技支撑计划项目“德兴铜矿资源高效开发 利用关键技术研究(2007BAB22801。以德兴铜矿自产的高铜高铼辉钼精矿为 研

36、究对象,进行辉钼精矿湿法分解新工艺研究,为发展环境友好的钼湿法冶金新 工艺提供技术原型;研究萃取、离子交换等分离富集技术,实现钼、铼、铜的高 效分离与综合回收。1.2辉钼矿氧化分解工艺焙烧一氨浸工艺是钼的经典冶金工艺,焙烧的目的是使辉钼矿中二硫化钼的 钼硫分离开来,使不溶于氨水的二硫化钼经过焙烧后转化为易溶于氨水的三氧化 钼。具体工艺流程见图1-231。2博士学位论文 第一章绪论 辉铝精矿T工业M003(焙砂T_一残渣厂碱溶或酸溶回收Mo钼酸氨溶液渣(含Cu、Fe、等硫化物纯钼酸氨溶液仲钼酸铵=图1-2钼提取的经典工艺流程该工艺是将辉钼矿在600-,700下进行氧化焙烧,得到的钼焙砂(主成分

37、为M003经氨浸、净化、酸沉、结晶等工序处理,转化成为钼酸铵产品。20世纪60-,70年代期间,世界上几乎90%的纯钼化合物的生产都采用此工艺【2牝81, 主要原理见方程式1.1:MoS2+3.502=M003+2S02(11 3博士学位论文 第一章绪论浸出是使工业M003粉中可溶钼溶于氨水,生成钼酸铵溶液,其反应方程式 见式1.2:M003+2NH3-H20=(NH42M004+H20(1-2 其它不溶性杂质,如CalVl004、PbM004、Si02、Fe203等残留在渣中,达到 钼和大部分杂质分离。氨浸出在固液比0.52.5,温度仲胺叔胺的顺序下降。季铵不能发生直接配位的反应。(4鳌合萃取剂鳌合萃取剂广泛应用在分析化学中,具有