摘要
钴白合金是铜钴氧化矿经还原熔炼得到的复杂合金产物,主要含有Co,Fe,Cu和Si,其他杂质元素的含量较低。目前,常压酸浸法被广泛地用于处理钴白合金,主要以硫酸和盐酸等强酸为浸出剂,在浸出过程中,在Co和Cu被浸出的同时,大量的Fe也进入到溶液中;该工艺存在有价金属回收率低,酸溶液中除铁困难等问题。鉴于此,进行了钴白合金常压磷酸选择性浸出Co和Cu,同时生产二水合磷酸铁的研究,并研究了磷酸浓度、双氧水添加量、浸出温度、浸出时间等因素对Co和Cu选择性浸出的影响。结果表明:在磷酸浓度为2.5 mol·L^(-1),温度为80℃,双氧水添加量为7.5%(体积分数),浸出时间为120 min,液固比(L/S=磷酸溶液(ml)/钴白合金(g))为12∶1的条件下,钴白合金中Co和Cu的浸出率分别达到99.6%和99.3%,Fe的浸出率仅为0.7%。Fe主要以二水合磷酸铁的形式存在于浸出渣中。该工艺实现了Co和Cu的选择性浸出以及Fe的资源化回收。
In recent years,with the rapid increase in demand for cobalt and the gradual consumption of cobalt ore,it was increasingly important to recover cobalt from cobalt-containing secondary resources,such as waste batteries,catalysts,cobalt bearing alloy,etc.Cobalt white alloy is a cobalt-bearing by-product obtained in the process of reduction of copper-cobalt oxide ore or pyrometallurgy of lead.The alloy mainly contains cobalt,iron copper and silicon,while other metal elements are low.Atmospheric acid leaching was often used to treat cobalt white alloy to recover valuable metals in recent years.The leaching was carried out in a strong acid solution such as sulfuric acid or hydrochloric acid.Due to the chemical stability of cobalt white alloy,the leaching can only be carried out in a high concentration acid solution.In the leaching process,cobalt and copper were leached while a large amount of iron was also dissolved into the solution,which cannot achieve the selective leaching of cobalt and copper from cobalt white alloy.Besides,iron removal from the high acid solution was very difficult,and the process led to the loss of valuable metals.In view of this,it may be a good alternative to selectively leach cobalt and copper from cobalt white alloy with phosphoric acid.In this process,cobalt and copper were selectively leached into the solution,while iron existed as phosphate in the leaching residue.It was necessary to systematically explore the effects of various factors on the selective leaching of cobalt and copper in order to obtain the optimum conditions when atmospheric phosphoric acid leaching was used to treat cobalt white alloy.The cobalt white alloy used in the experiment was obtained from the Democratic Republic of Congo.The sample was systematically analyzed by means of inductively coupled plasma emission spectrometer(ICP-OES),X-ray diffraction analysis(XRD)and scanning electron microscope(SEM).Cobalt white alloy was a complex alloy eutectic containing cobalt(39.89%),iron(40.30%),copper(7.80%)and silicon(5.61%),and the main components minerals were silicon cobalt,ferrosilicon alloy and copper.In addition,the effects of phosphoric acid concentration,hydrogen peroxide content,temperature,time,and liquid-solid ratio on the selective leaching were explored.The result showed that phosphoric acid concentration had an important effect on the selective leaching of cobalt white alloy.In the range of 1~2.5 mol·L^(-1),the leaching efficiencies of cobalt and iron increased with the increase of phosphoric acid concentration,while iron was not leached.With further increase of phosphoric acid,the leaching efficiencies of cobalt and copper remained unchanged,while the leaching of iron gradually increased,which was unfavorable for selective leaching.When the phosphoric acid concentration was 2.5 mol·L^(-1),the leaching of cobalt,copper and iron were 98.3%,97.5%and 8.9%respectively.With the increase of hydrogen peroxide content,the leaching efficiencies of cobalt and copper increased rapidly,while the leaching efficiency of iron increased first and then decreased.When the content of hydrogen peroxide was 7%(volume fraction),the leaching of cobalt,copper and iron were 98.8%,98.1%and 6.4%,respectively.With the increase of temperature,the leaching efficiencies of cobalt and copper increased gradually,while the leaching of iron decreased gradually.When the temperature was 80℃,the leaching efficiencies of cobalt,copper and iron were 99.1%,98.9%and 1.7%,respectively.When the leaching time was more than 120 min,the leaching efficiencies of cobalt and copper were more than 99%,while the leaching of iron was less than 1.1%.When the liquid-solid ratio was 12∶1,the leaching efficiencies of cobalt and copper reached 99.5 and 99.2%,while the leaching of iron was 0.8%.By the analysis of the leaching behavior of cobalt white alloy,the optimum conditions for the leaching of phosphoric acid at atmospheric pressure were determined as follows:phosphoric acid concentration of 2.5 mol·L^(-1),leaching temperature of 80℃,hydrogen peroxide content of 7.5%,leaching time of 120 min,and liquid-solid ratio of 12∶1.Under the optimum process conditions,the leaching efficiencies of cobalt,copper and iron reached 99%,98%and 0.7%,respectively,which ensured the selective leaching of cobalt and copper.The leaching residue was systematically analyzed by XRD and SEM.The phase of the leaching residue was FePO_(4)·2H_(2)O,and it distributed as irregular lamellar.The weight loss behavior of the residues was examined at 50~300℃in argon by thermogravimetric analysis.The weight loss of the sample was 19.3%(≈2H_(2)O)during the heating process,which indicated that the content of FePO_(4)·2H_(2)O was high.pH of the leaching solution had an important effect on the selective leaching of cobalt and copper.The lower the crystallization pH_(0) was,the easier it was to produce precipitation.In the range of phosphoric acid concentration of 1~4 mol·L^(-1),the crystallization pH_(0) of cobalt(Co^(2+))and copper(Cu^(2+))was more than 3.5,while the crystallization pH_(0) of iron(Fe^(3+))was less than 0.33.When the concentration of phosphoric acid was 2.5 mol·L^(-1),pH of the solution after leaching was 1.1.Cobalt(Co^(2+))and copper(Cu^(2+))were dissolved in the solution,while iron(Fe^(3+))precipitated in the form of FePO_(4)·2H_(2)O by reacting with phosphate which realized the selective leaching of cobalt white alloy.
作者
张丁川
赵中伟
孙丰龙
刘旭恒
陈星宇
李江涛
何利华
Zhang Dingchuan;Zhao Zhongwei;Sun Fenglong;Liu Xuheng;Chen Xingyu;Li Jiangtao;He Lihua(School of Metallurgy and Environment,Central South University,Changsha 410083,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2023年第11期1515-1524,共10页
Chinese Journal of Rare Metals
基金
2022年镍钴资源高效利用及新产品开发创新联合体项目(22ZD6GC017)
国家自然科学基金项目(92062223)资助
关键词
钴白合金
常压浸出
二水合磷酸铁
钴
铜
cobalt white alloy
atmospheric leaching
iron phosphate dihydrate
cobalt
copper
作者简介
张丁川(1988-),男,河南周口人,博士研究生,研究方向:含钴二次资源的回收,E-mail:ZhangDC@csu.edu.cn;通信作者:赵中伟,教授,电话:0731-88830476,E-mail:zhaozw@csu.edu.cn
