Inhibition of acid mine drainage and immobilization of heavy metals from copper flotation tailings using a marble cutting waste

Acid mine drainage (AMD) with high concentrations of sulfates and metals is generated by the oxidation of sulfide bearing wastes. CaCO₃-rich marble cutting waste is a residual material produced by the cutting and polishing of marble stone. In this study, the feasibility of using the marble cutting waste as an acid-neutralizing agent to inhibit AMD and immobilize heavy metals from copper flotation tailings (sulfide- bearing wastes) was investigated. Continuous-stirring shake-flask tests were conducted for 40 d, and the pH value, sulfate content, and dissolved metal content of the leachate were analyzed every 10 d to determine the effectiveness of the marble cutting waste as an acid neutralizer. For comparison, CaCO₃ was also used as a neutralizing agent. The average pH value of the leachate was 2.1 at the beginning of the experiment (t = 0). In the experiment employing the marble cutting waste, the pH value of the leachate changed from 6.5 to 7.8, and the sulfate and iron concentrations decreased from 4558 to 838 mg/L and from 536 to 0.01 mg/L, respectively, after 40 d. The marble cutting waste also removed more than 80wt% of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) from AMD generated by copper flotation tailings.     

Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains and microbial community succession analysis

Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains was carried out by mixed cultures on a small scale over a period of 210 d. Lump ores as a framework were loaded at the bottom of the ore heap. The overall copper leaching rates of tailings and lump ores were 57.10wt% and 65.52wt%, respectively. The dynamic shifts of microbial community structures about attached microorganisms were determined using the Illumina MiSeq sequencing platform based on 16S rRNA amplification strategy. The results indicated that chemolithotrophic genera Acidithiobacillus and Leptospirillum were always detected and dominated the microbial community in the initial and middle stages of the heap bioleaching process; both genera might be responsible for improving the copper extraction. However, Thermogymnomonas and Ferroplasma increased gradually in the final stage. Moreover, the effects of various physicochemical parameters and microbial community shifts on the leaching efficiency were further investigated and these associations provided some important clues for facilitating the effective application of bioleaching.     

利用自动解离分析方法研究硫化铜尾矿的矿物学特征:谦比希铜矿尾矿的实例研究

As ore grades constantly decline, more copper tailings, which still contain a considerable amount of unrecovered copper, are expected to be produced as a byproduct of froth flotation. This research reveals the occurrence mechanism of copper minerals in typical copper sulfide tailings using quantitative mineral liberation analysis (MLA) integrated with scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS). A comprehensive mineralogical characterization was carried out, and the results showed that almost all copper minerals were highly disseminated within coarse gangue particles, except for 9.2wt% chalcopyrite that occurred in the 160–180 μm size fraction. The predominant copper-bearing mineral was chalcopyrite, which was closely intergrown with orthoclase and muscovite rather than quartz. The flotation tailings sample still contained 3.28wt% liberated chalcopyrite and 3.13wt% liberated bornite because of their extremely fine granularity. The SEM–EDS analysis further demonstrated that copper minerals mainly occurred as fine dispersed and fully enclosed structures in gangue minerals. The information obtained from this research could offer useful references for recovering residual copper from flotation tailings.     

Use of centrifugal-gravity concentration for rejection of talc and recovery improvement in base-metal flotation

The possibility of using a centrifugal-gravity concentrator to reject Mg-bearing minerals and minimize metal losses in the flotation of base metals was evaluated. Sample characterization, batch scoping tests, pilot-scale tests, and regrind-flotation tests were conducted on a Ni flotation tailings stream. Batch tests revealed that the Mg grade decreased dramatically in the concentrate products. Pilot-scale testing of a continuous centrifugal concentrator (Knelson CVD6) on the flotation tailings revealed that a concentrate with a low mass yield, low Mg content, and high Ni upgrade ratio could be achieved. Under optimum conditions, a concentrate at 6.7% mass yield was obtained with 0.85% Ni grade at 12.9% Ni recovery and with a low Mg distribution (1.7%). Size partition curves demonstrated that the CVD also operated as a size classifier, enhancing the rejection of talc fines. Overall, the CVD was capable of rejecting Mg-bearing minerals. Moreover, an opportunity exists for the novel use of centrifugal-gravity concentration for scavenging flotation tailings and/or after comminution to minimize amount of Mg-bearing minerals reporting to flotation.     

氰化尾渣浮选回收过程中黄铜矿的界面特性研究

氰化尾渣是氰化提金过程中产生的固体废弃物,同时也是高价值的二次资源,含有大量的铜、铅、锌等有价元素。由于氰化过程长时间的充气搅拌,氰化尾渣的矿物界面发生严重的改性,但是关于这方面的研究较少。本文针对某高铜铅氰化尾渣浮选过程中存在铜铅难分离及铜回收率低等问题开展黄铜矿界面性质研究,采用的研究方法包括粒度分析仪、XRD分析、SEM–EDS微界面分析、FTIR分析、界面洗脱及浮选实验等。实验结果表明部分黄铜矿表面致密包裹一层细粒的方铅矿,导致黄铜矿表现为类似于方铅矿的浮选特性,导致这种现象的原因是黄铜矿表面被非极性油污染。不能被浮选回收的黄铜矿表面包裹一层铁矾类似物,导致黄铜矿表面被钝化而不利于药剂的吸附。通过研究可知氰化尾渣中黄铜矿界面容易被杂质污染及氧化层包裹,导致其难于被浮选回收。     

超细氰化尾渣中铜铅矿物颗粒界面性质

山东某冶炼厂氰化尾渣无法实现铜铅分选,通过XRD、激光粒度仪、浮选实验、FTIR、SEM-EDS、金相显微镜等方法,研究了氰化尾渣铜铅矿物颗粒界面性质.结果表明,渣中主要矿物为方铅矿、黄铜矿、黄铁矿、闪锌矿,粒度小于38μm质量分数为95.61%.氰化尾渣中的方铅矿和黄铜矿表面含有大量油状物,此油状物被证明是机械润滑油.黄铜矿表面吸附大量润滑油,造成黄铜矿无法被氰化物抑制.细颗粒方铅矿通过疏水作用力包裹在黄铜矿表面,导致铜铅无法分选.     

Beneficiation of the gold bearing ore by gravity and flotation

Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. Gold bearing ore samples were taken from Gümüşhane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.     

Semi-industrial experimental study on bauxite separation using a cell–column integration process

The cyclonic-static micro-bubble flotation column (FCSMC) is a highly efficient mineral processing equipment. In this study, a cell-column (FCSMC) integration process was investigated for the separation of bauxite and its feasibility was analyzed on a theoretical basis. The properties of low-grade bauxite ore from Henan Province, China were analyzed. Parameters such as reagent dosage, scraping bubble time, and pressure of the circulating pump during the sorting process were investigated and optimized to improve the flotation efficiency. On the basis of these parameters, continuous separation experiments were conducted. Bauxite concentrate with an aluminum-to-silicon (A/S) mass ratio of 6.37 and a 77.63wt% recovery rate were achieved via a flow sheet consisting of “fast flotation using a flotation cell, one roughing flotation and one cleaning flotation using flotation columns”. Compared with the full-flotation-cells process, the cell–column integration process resulted in an increase of the A/S ratio by 0.41 and the recovery rate by 17.58wt%. Cell–column integration separation technology represents a new approach for the separation of middle-to-low-grade bauxite ore.     

Recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation: process optimization and mineralogical study

Currently, the majority of copper tailings are not effectively developed. Worldwide, large amounts of copper tailings generated from copper production are continuously dumped, posing a potential environmental threat. Herein, the recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation was conducted; process optimization was carried out, and the corresponding mineralogy was investigated. The reduction time, reduction temperature, reducing agent (coal), calcium chloride additive, grinding time, and magnetic field intensity were examined for process optimization. Mineralogical analyses of the sample, reduced pellets, and magnetic concentrate under various conditions were performed by X-ray diffraction, optical microscopy, and scanning electron microscopy-energy-dispersive X-ray spectrometry to elucidate the iron reduction and growth mechanisms. The results indicated that the optimum parameters of iron recovery include a reduction temperature of 1150℃, a reduction time of 120 min, a coal dosage of 25%, a calcium chloride dosage of 2.5%, a magnetic field intensity of 100 mT, and a grinding time of 1 min. Under these conditions, the iron grade in the magnetic concentrate was greater than 90%, with an iron recovery ratio greater than 95%.     

钛铁矿海滨砂矿尾矿的浮选试验研究

对广西北海地区的钛铁矿砂矿尾矿进行了系统浮选试验研究,钛铁矿砂矿尾矿由原矿经过重选和磁选得到.研究表明,Pb(NO_3)_2对钛铁矿有活化作用,主要是由于Pb2+与钛铁矿发生特性吸附,提高了油酸钠对钛铁矿的捕收能力.以硫酸和水玻璃作为调整剂,Pb(NO_3)_2作为活化剂,油酸钠作为捕收剂进行浮选,在硫酸用量900 g/t,水玻璃用量400 g/t,Pb(NO_3)_2用量30 g/t,油酸钠用量450 g/t的药剂制度条件下,经过一次粗选、两次精选的闭路浮选流程,可得到TiO_2品位为39.55%,回收率为54.61%的钛精矿.     

硫化锌精矿加压酸浸渣回收工艺及其环境影响分析

以硫化锌精矿加压酸浸渣为研究对象,系统的分析了加压酸浸渣浮选回收硫精矿,浮选尾矿经两段浸出、氧化除铁、锌粉置换和蒸发浓缩等工序回收七水硫酸锌的工艺过程,并分析了该过程产生的废气、废水、废渣和噪声等对周围环境的影响。     

稳态浮选流程的计算机仿真

笔者以Kelsall的快慢浮离散分布速率常数模型为基础建立单槽浮选机模块ONECEL,并在微型机上建立通用的稳态浮选流程仿真器SIMFLOT,可以仿真任意结构的浮选流程。笔者还以从实际值和计算值差的加权平方和为目标函数,采用SUMT混合罚函数法估计模型参数,并编制了相应的程序ESTIFLOT。实例以德兴铜矿生产数据作为仿真标准条件,原始数据经物料平衡程序包CSIMMBAL处理,用ESTIFLOT估计出模型参数,最后用SIMFLOT进行仿真运算,仿真结果令人满意。     

铝土矿浮选产品中捕收剂的分析

采用溶剂解吸提取预处理和紫外分光光度法研究了铝土矿浮选产品中微量脂肪酸捕收剂的分析方法．通过对比三氯乙烯、四氯乙烯、三氯甲烷、四氯化碳和正己烷5种溶剂的解吸提取性能,提出在液固比为2．5ml／g的条件下,以三氯甲烷解吸提取、富集样品中的捕收剂,以紫外分光光度法进行铝土矿浮选产品中微量捕收剂的定量分析,并对其可靠性进行了检验．研究结果表明在5种解吸溶剂中,三氯甲烷的解吸提取性能最佳,能在液固比为0．5～5．0mI/g的范围内解吸并富集铝土矿浮选产品表面的捕收剂．用该方法分析捕收剂含量为100～1000g/t的铝土矿浮选产品,测定结果的变异系数和回收率分别为1．4％～1．6％和97％～103％,具有重现性好、结果准确、操作简便快捷的特点     

铀矿尾渣胶结充填体塌落度影响因素及预测模型

采用生石灰中和后的铀矿尾渣为试验骨料,水泥为胶结剂,试验了不同渣浆质量浓度和灰渣质量比条件下尾渣胶结充填体试件塌落度。利用自适应神经模糊推理系统(adaptive neuro-fuzzy inference system,ANFIS)预测不同渣浆质量浓度和灰渣质量比条件下塌落度。试验结果和模型预测结果表明,在同等条件下,铀矿尾渣胶结充填体的塌落度与渣浆质量浓度和灰渣质量比均成反比;随着渣浆质量浓度变小,铀矿尾渣胶结充填体流动性变大,如果再降低灰渣质量比,铀矿尾渣胶结充填体会出现明显离析现象;铀矿尾渣胶结充填体塌落度ANFIS模型的预测精度较高,结果唯一且可靠;如果不同矿山铀尾渣物理参数相似性较高,则已知的铀矿尾渣胶结充填体塌落度ANFIS模型可以预测该矿山尾渣胶结充填体的塌落度。     

鞍山式赤铁矿石反浮选尾矿铁品位偏高机制

针对鞍山式赤铁矿石反浮选流程中存在的浮选尾矿铁品位偏高的问题,借助X射线衍射分析、化学多元素分析、粒度分析、扫描电子显微镜等检测手段,对选别流程中样品的化学多元素组成、物相组成、粒度分布及矿物的单体解离度进行了研究.结果表明,在各扫选尾矿中存在着一些单体解离高的微细铁矿物颗粒,其吸附在粗粒级脉石矿物表面,形成“载体浮选”进入到尾矿中,造成尾矿铁品位偏高.     

Use of mesophilic and thermophilic bacteria for the improvement of copper extraction from a low-grade ore

Bioleaching was examined for copper extraction from a low grade ore using mesophilic and moderate thermophilic bacteria. Five equal size columns were used for the leaching of the ore. Sulfuric acid solution with a flow rate of 3.12 L·m-2·h-1 and pH 1.5 passed through each column continuously for 90 d. In the first and the second column, bioleaching was performed without agglomeration of the ore and on the agglomerated ore, respectively. 28wt% of the copper was extracted in the first column after 40 d, while this figure was 38wt% in the second column. After 90 d, however, the overall extractions were almost the same for both of them. Bioleaching with mesophilic bacteria was performed in the third column without agglomeration of the ore and in the fourth column on the agglomerated ore. After 40 d, copper extractions in the third and the fourth columns were 62wt% and 70wt%, respectively. Copper extractions were 75wt% for both the columns after 90 d. For the last column, bioleaching was performed with moderate thermophilic bacteria and agglomerated ore. Copper extractions were 80wt% and 85wt% after 40 and 90 d, respectively. It was concluded that crushing and agglomeration of the ore using bacteria could enhance the copper extraction considerably.     

海南某金矿尼尔森重选-浮选试验

以海南某石英脉型金矿石为原料,进行尼尔森重选-浮选试验研究.通过GRG试验得出金矿中重选可回收金质量分数为80.88%.通过条件试验确定了该矿石尼尔森重选-浮选的最佳条件为:磨矿细度-74μm占80%,相对离心力60g,反冲水压16kPa,矿浆质量分数40%,戊基黄药用量200g/t,浮选时间5 min.原矿石品位9.8g/t,利用尼尔森选矿机一次分选可得品位230g/t,金回收率80.30%的重选精矿.重选尾矿品位2.0g/t,经过一次粗选一次精选三次扫选处理,可得浮选精矿品位57.3g/t,浮选金作业回收率75.66%.经尼尔森重选-浮选流程处理后,尾矿金品位降至0.5g/t,全流程金总回收率95.21%.     

Purification of specularite by centrifugation instead of flotation to produce iron oxide red pigment

This study used specularite, a high-gradient magnetic separation concentrate, as a raw material in reverse flotation.An iron concentrate with a grade of 65.1 wt% and a recovery rate of 75.31% were obtained.A centrifugal concentrator served as the deep purification equipment for the preparation of iron oxide red pigments, and its optimal rotating drum speed, feed concentration, and other conditions were determined.Under optimal conditions, a high-purity iron oxide concentrate with a grade of 69.38 wt% and a recovery rate of 80.89% were obtained and used as a raw material for preparing iron oxide red pigment.Calcining with sulfuric acid produced iron red pigments with different hues.Simultaneously, middlings with a grade of 60.20 wt% and a recovery rate of 17.51% were obtained and could be used in blast furnace ironmaking.High-value utilization of specularite beneficiation products was thus achieved.     

N-十二烷基-1,3-丙二胺在赤铁矿反浮选中的应用

通过单矿物试验考察了N-十二烷基-1,3-丙二胺(ND13)对赤铁矿和石英的浮选行为,结果表明,ND13对石英具有良好的捕收性能,在捕收剂用量为50mg/L,pH=7～10时,石英回收率达93%以上.人工混合矿分选试验结果表明,ND13对赤铁矿和石英质量比为1∶1(铁品位为35%)的人工混合矿具有一定的分选效果,在ND13用量为66.7mg/L,淀粉用量为6.67mg/L,pH=7.27的条件下,达到较好的分选效果,此时精矿中铁的回收率为86.35%,精矿的铁品位为62.78%,尾矿的铁品位为9.21%.动电位和红外光谱分析结果表明,ND13主要以静电和氢键作用在矿物表面发生吸附.     

关于溶剂浮选法回收湿法磷酸中碘的氧化剂

在用溶剂浮选法回收湿法磷酸中碘的过程中,氧化剂的选择是重要的。实验研究结果表明,随着氧化剂用量的增加,氧化电位升高,而氧化率也先上升,达到一最大值,然后下降,因此,对碘的回收存在一适宜的氧化剂用量。