The effect of regrind mills on the separation of chalcopyrite from pyrite in cleaner flotation

Stirred mills have been widely used for regrinding and are more energy efficient than tumbling mills. These two types of mills present different particle breakage mechanisms and redox environments during grinding. In this study, the effect of regrinding with these two types of mills on the separation of chalcopyrite from pyrite in the cleaner stage was studied. A laboratory rod mill and a laboratory stirred mill were used to regrind rougher flotation concentrates. It was found that chalcopyrite and pyrite exhibited different flotation behavior after regrinding with the rod mill and the stirred mill, resulting in different separability of chalcopyrite from pyrite. The mechanism underpinning this phenomenon was investigated by a range of techniques including dissolved oxygen demand measurements, X-ray photoelectron spectroscopy (XPS) and Time of flight secondary ion mass spectrometry (ToF-SIMS). It was found that the two mills produced different surface oxidation and pyrite activation by copper ions which determined the separation of chalcopyrite from pyrite. This study demonstrates that the selection of a regrind mill should not only depend on its energy efficiency but also the property of surfaces produced for subsequent flotation.     

Importance of oxidation during regrinding of rougher flotation concentrates with a high content of sulfides

The objective of this study is to understand the flotation behavior of copper and gold minerals after regrinding the rougher flotation concentrate with a high pyrite content. It was found that low Eh and dissolved oxygen (DO) were produced after regrinding due to the quick consumption of oxygen by the large amount of fresh pyrite surfaces created, resulting in poor flotation of copper and gold and their selectivity against pyrite. A number of methods were used to provide an oxidizing condition, including pre-aeration before flotation, regrinding in an oxidizing condition, and addition of different oxidizing agents during regrinding. It was found that all the oxidizing methods improved the flotation of copper and gold, however, the effectiveness of these methods varied from case to case. This study demonstrates the importance of oxidation during or after regrinding for the flotation of rougher flotation concentrates with high sulfide contents.     

Operating strategies to maximise gold recovery at Telfer

On average, the difference in recovery between copper and gold is 15% among the large scale copper/gold operations. At Telfer, a number of operating strategies have been implemented together with a sequential flotation circuit design to maximise gold recovery. The main operating strategies include targeting a primary grind size optimum for copper recovery, designing and operating the main flotation circuit as copper and pyrite sequential flotation, targeting a minimum saleable concentrate copper grade, allowing a portion of pyrite/gold recovered into the copper concentrate and leaching the pyrite concentrate to extract the gold. These operating strategies have lifted the recovery of both copper and gold above 90%. There are opportunities to further improve the metallurgical performance at Telfer, including a single stage of cleaning of the copper rougher concentrate, regrinding of the copper scavenger concentrate prior to cleaning and regrinding of the pyrite rougher concentrate followed by additional copper/gold flotation prior to pyrite leaching.     

从某铁矿尾矿库中浮选回收铜硫矿物的研究

采用异步浮选工艺, 从某铁矿尾矿库中综合回收铜硫矿物。第一段粗选在自然pH条件下进行, 选出易浮的黄铜矿、辉铜矿和黄铁矿; 第二段粗选采用碱性介质, 硫化氧化严重的黄铜矿、辉铜矿以及黄铁矿, 应用诱导浮选将硫化矿物富集、回收; 以Y01-Y02-石灰组合药剂作为铜-硫分离调整剂, 最终得到铜精矿中铜品位13.38％, 硫精矿中硫品位42.55%的闭路试验指标。     

The effect of surface oxidation of copper sulfide minerals on clay slime coating in flotation

The industry is well aware of the difficulty in treating copper ores in the presence of clay minerals. In this study, the effect of bentonite on the flotation of chalcopyrite (a primary copper sulfide mineral) and chalcocite (a secondary copper sulfide mineral) was investigated in terms of surface coating. Based on the flotation of copper ores containing both chalcopyrite and chalcocite, the flotation of chalcopyrite and chalcocite single minerals in the presence and absence of bentonite, and the zeta potential measurement of chalcopyrite, chalcocite and bentonite, it was found that the oxidation of chalcopyrite and chalcocite had a different effect on their interaction with bentonite. Under the normal grinding and flotation condition, significant oxidation occurred on the surface of chalcocite which was electrostatically attractive to bentonite resulting in bentonite slime coating and the depressed flotation of chalcocite. The reduction of oxidation on chalcocite could mitigate bentonite slime coating due to electrostatic repulsion between unoxidized chalcocite and bentonite. Unlike chalcocite, chalcopyrite with and without surface oxidation exhibited an electrostatic repulsion to bentonite. Its flotation was less affected by bentonite slimes.     

The effect of particle breakage mechanisms during regrinding on the subsequent cleaner flotation

Stirred mills have been widely used for regrinding, and are acknowledged to be more energy efficient than tumbling mills. These two types of mills present different particle breakage mechanisms during grinding. In this study, the effect of regrinding by both mills on surface properties and subsequent mineral flotation was studied, using chalcocite as the mineral example. A rod mill and a stirred mill with the same stainless steel media were used to regrind rougher flotation concentrates. Different chalcocite flotation recovery was achieved in the cleaner stage after regrinding in tumbling and stirred mills. The factors contributing to the different recovery included particle size, the amount of created fresh surfaces, surface oxidation and the redistribution of collector carried from rougher flotation. All the factors were examined. It was determined that the predominating factor was the different distribution of collector resulting from different particle breakage mechanisms in the stirred and tumbling mills, in line with ToF-SIMS analysis. In the tumbling mill, the impact particle breakage mechanism predominates, causing the collector to remain on the surface of newly produced particles. In the stirred mill, the attrition breakage removes collector from the surface, and decreases particle floatability. Furthermore, the type of grinding media in the stirred mill also influences the subsequent flotation, again due to the change of particle breakage mechanisms. The results of this study demonstrate that the selection of regrinding mills and grinding media should not only depend on the required energy efficiency, but also on the properties of the surfaces produced for subsequent flotation.     

The influence of pyrite content on the flotation of chalcopyrite/pyrite mixtures

In the flotation of copper ores, several processing plants report that copper recovery is affected by the proportion and reactivity of pyrite in the ore, with the effect becoming more intense when the feed particles are finer as a result of regrinding. In this work, a mixed model mineral system consisting of chalcopyrite (CuFeS₂) and pyrite (FeS₂) with varying pyrite content (20–80 wt.%) was used to investigate the effect of pyrite on the pulp chemistry and chalcopyrite recovery. Flotation tests showed that chalcopyrite flotation rate, recovery and grade, as well as the pulp oxidation potential, decreased with increasing pyrite content whilst pyrite recovery increased. Surface analysis (XPS, ToF-SIMS and EDTA) indicated that copper activation of pyrite increased with increasing pyrite content, facilitating pyrite recovery. The decrease in chalcopyrite recovery can be attributed to increased surface oxidation.     

安徽某铁尾矿中铜硫的选矿回收研究

针对安徽某铁矿磁选尾矿中铜矿物粗细不均,次生硫化铜含量较高,且部分黄铜矿被黄铁矿包裹等特点,在原铜硫混浮-铜硫分离工艺前进行了增设快速浮铜工艺环节的研究,并对混精再磨、分离工艺进行了优化研究。采用试验确定的半优先浮铜闭路试验流程处理该试样,可获得铜品位21.48%、回收率达82.85%的铜精矿,以及硫品位为48.34%、回收率为84.43%的硫精矿,试验铜回收率较生产平均铜回收率高10个百分点以上。     

Effect of electrolytes on the flotation of copper minerals in the presence of clay minerals

Clay minerals have a deleterious effect on flotation. In a previous study (Peng and Zhao, 2011), the authors found that the flotation of secondary copper minerals such as chalcocite was more affected by clay minerals than the flotation of primary copper minerals such as chalcopyrite due to stronger surface oxidation resulting in an electrostatic attraction to clay particles. In this current study, the intention was to use electrolytes to mitigate the adverse effect of clay minerals on chalcocite flotation. A copper ore mainly containing chalcocite was examined. In fresh tap water, kaolinite significantly depressed chalcocite flotation. However, with an increase in the electrolyte concentration, the recovery of chalcocite was increased. It is concluded that the electrolytes reduce the electrostatic attraction between kaolinite and chalcocite so that the surface coating of kaolinite on chalcocite surfaces may be mitigated leading to improved chalcocite flotation. It is interesting to find that anions and cations with a greater atomic size had a more beneficial effect which may be associated with their tendency to modify surface hydrophobicity.     

某低品位铜钼矿工艺矿物学及选矿工艺研究

青海某铜钼矿含钼0.084%,铜含量0.067%。工艺矿物学研究表明,原矿中钼主要以辉钼矿形式存在,铜以黄铜矿、辉铜矿及斑铜矿等形式赋存。针对矿石性质,结合探索实验,最终采用铜钼优先浮选工艺处理该矿石。在磨矿细度为-74μm 70%条件下,经一次粗选一次扫选两次空白精选得钼粗精矿,钼粗精矿再磨后经三次精选获得了钼品位50.21%、回收率85.21%的钼精矿;钼浮选尾矿用硫酸铜活化后经一次粗选一次扫选四次精选,获得了品位15.32%、回收率54.92%的铜精矿,实现了有价元素的综合回收。     

Flotation separation of copper sulphides from arsenic minerals at Rosebery copper concentrator

The removal of arsenic bearing minerals from concentrates is becoming more important as environmental laws become ever stricter with regard to smelter emissions. The onus is shifting to concentrate producers to remove these minerals from their product, with penalties applying to materials containing greater than background amounts.The arsenic content of Rosebery copper flotation feed is mainly present as arsenopyrite (FeAsS), containing approximately 46.0% arsenic with the remainder of the arsenic in copper sulphosalts (tennantite (Cu₁₂As₄S₁₃)), in a solid solution series with tetrahedrite (Cu₁₂Sb₄S₁₃). Tennantite contains approximately 20.3% arsenic. Characterisation of the rougher and cleaner concentrates obtained during a plant survey showed that the arsenopyrite was appropriately rejected in the copper flotation circuit. However, tennantite showed similar flotation behaviour to the copper sulphide minerals so that the high arsenic content of the final copper concentrate was mainly in the copper sulphosalts. In this study, regrinding the copper rougher concentrate was investigated to reject tennantite in cleaner flotation. It was found that although finer grinding increased the mass fraction in the ultrafine fraction, the tennantite liberation only increased slightly. The copper selectivity against arsenic was improved significantly although the recovery of copper, silver and arsenic was lower. The difference in floatability of copper sulphide minerals and tennantite appears to increase at finer sizes. In this study, pH and Eh were also manipulated to further improve the selectivity of copper flotation against tennantite at fine particle sizes with some promise. In order to find an application in the Rosebery circuit, any changes must have a net economic benefit and the trade-offs and implications are discussed in this paper.     

Assessment of the floatability of chalcopyrite,molybdenite and pyrite using biosolids and their main components as collectors for greening the froth flotation of copper sulphide ores

Biosolids and representative compounds of their main components – humic acids, sugars, and proteins – have been tested as possible environment-friendly collectors and frothers for the flotation of copper sulphide ores. The floatability of chalcopyrite and molybdenite – both valuable sulphide minerals present in these ores – as well as non-valuable pyrite was assessed through Hallimond tube flotation tests. Humic acids exhibit similar collector ability for chalcopyrite and molybdenite as that of a commercial collector (Aero 6697 promoter). Biosolids show more affinity for pyrite. The copper recovery (85.9%) and copper grade (6.7%) of a rougher concentrate obtained using humic acids as main collector for the flotation of a copper sulphide ore from Chile, were very similar to those of a copper concentrate produced by froth flotation under the same conditions with a xanthate type commercial collector. This new and feasible end-use of biosolids and humic acids should be new environment-friendly organic froth flotation agents for greening the concentration of copper sulphide ore. Now, further research is needed in order to scale current laboratory assays to operational mining scales to determine efficiencies to industrial scale.     

硫化铜矿诱导浮选的研究与应用

考察了黄铜矿和黄铁矿的诱导浮选行为，并对其机理进行探讨。研究表明，黄铜矿具有良好的自诱导可浮性；黄铁矿的自诱导可浮性差，但具有良好的硫化钠诱导可浮性。不同的诱导浮选特性可以使硫化铜矿的铜硫分离更具选择性。     

铜硫分离中银的选择性导向回收

为了研究新型抑制剂在铜硫分离过程中对银浮选行为的影响, 采用石灰和LY作为硫抑制剂, 通过6种动力学模型, 分别考察了低碱和高碱环境下铜、银和铁的浮选回收率及动力学行为。结果表明, 6种动力学模型均可较好地拟合试验数据。石灰选择性较差, 在低碱性介质中对黄铁矿的抑制效果较弱, 在强碱性介质中不利于铜和银矿物的回收; 而LY在铜硫分离过程中表现出良好的选择性, 它可以在低碱和高碱环境下强烈抑制黄铁矿, 并在弱碱性矿浆中实现铜硫的高效分离, 同时诱导独立银矿物定向富集至铜精矿产品中。     

从某硫精矿中回收铜的试验研究

某硫精矿含铜0.41%,铜矿物主要为黄铜矿和辉铜矿,硫矿物主要是磁黄铁矿,其次是黄铁矿,脉石矿物为少量蛇纹石、滑石、绿泥石等易泥化矿物,经镜下鉴定铜矿物与黄铁矿关系密切,基本以较粗的连生体形式存在,而磁黄铁矿基本不含铜。综合考虑矿石性质,确定采用"磁选脱硫—脱泥—浮铜"流程回收铜,全流程获得铜精矿铜品位20.26%,铜回收率73.41%。     

汝阳东沟钼矿钼粗选工艺条件研究

研究了汝阳东沟钼矿磨矿细度、粗选药剂制度及浮选时间等因素对钼矿选别效果的影响。钼原矿品位为0.130%时, 经过一粗一精一扫的粗选流程和两次再磨、六次精选的精选流程闭路试验, 取得了钼精矿品位53.26%, 回收率86.27%的较理想指标。     

新型有机抑制剂RC 在铜硫矿物浮选分离中的抑制作用

研究了新型有机抑制剂RC 在黄铜矿和黄铁矿浮选分离中的作用。单矿物浮选实验表明:这种抑制剂在整个pH 范围内, 对黄铁矿具有很好的抑制作用, 在黄铜矿的浮选实验中, 仅当pH ≈4 时, 抑制剂对黄铜矿产生了一定的抑制作用, 而在pH >4.5 时, 抑制剂对黄铜矿的浮选行为影响不大, 对黄铜矿抑制作用较弱。人工混合矿实验表明:RC 能有效实现铜硫矿物浮选分离, 使得铜精矿品位达到24.73 %, 回收率为80.36%。整个研究表明:在黄铜矿和黄铁矿浮选分离中, RC 不仅显示了很强的抑制黄铁矿的效果, 而且用量低、无毒、无污染, 是一种理想的铜硫选择性浮选分离抑制剂。     

以羟乙基纤维素为抑制剂浮选分离铜硫

为检验铜硫分离新型抑制剂HEC的有效性,并了解HEC作用效果的影响因素,以丁基黄药为捕收剂,对黄铜矿、黄铁矿纯矿物进行了浮选试验,并以HEC为抑制剂进行了实际矿物浮选试验。结果表明：①丁基黄药对黄铜矿的捕收能力强于黄铁矿,且几乎不受矿浆pH值的影响,在无抑制剂的情况下,高碱环境可抑制黄铁矿的上浮。②HEC可用于铜硫分离,用量为200 mg/L时可显著抑制黄铁矿,但对黄铜矿的抑制能力很弱。③抑制剂HEC适宜在pH=7的环境下浮选分离黄铜矿与黄铁矿的人工混合矿。④在分选内蒙古某铜硫矿石时,以HEC为铜硫分离黄铁矿的抑制剂,可获得铜品位为23.21%、铜回收率为81.75%的铜精矿,以及硫品位为13.20%、硫回收率80.83%的硫精矿,较好地实现了铜硫分离。     

某难选铜镍硫化矿选矿试验研究

某铜镍矿含铜0.23%、镍0.42%,属低品位硫化矿石。矿石中铜矿物大部分为黄铜矿,镍矿物主要为镍黄铁矿,其他金属矿物主要为黄铁矿、磁黄铁矿、磁铁矿。脉石矿物主要有橄榄石、辉石、斜长石、透闪石等。矿物学研究表明,该铜镍矿呈典型的浸染状构造,影响铜镍回收的主要矿物学因素是矿石中黄铜矿、镍黄铁矿的产出形式较为复杂、嵌布粒度较细、形态不甚规则。根据该矿石性质,采用BK303新型高效捕收剂,CMC作脉石矿物抑制剂,通过“两粗两扫三精-粗精矿再磨-中矿顺序返回”的工艺流程,成功实现了铜镍的高效浮选回收,闭路试验获得了铜品位3.29%、镍品位5.32%,铜回收率81.78%、镍回收率71.53%的铜镍混合精矿,取得了良好的浮选指标。     

乙硫氮作捕收剂时无机调整剂加药顺序对典型硫化矿物浮选的影响

研究了乙硫氮作捕收剂时无机调整剂硫酸锌、亚硫酸钠、硫化钠和硫酸铜不同加药顺序对典型硫化矿物黄铜矿、方铅矿、闪锌矿和黄铁矿浮选行为的影响。结果表明,调整剂与捕收剂的加药顺序对硫化矿物浮选的影响不同。与调整剂先加时相比,乙硫氮先加时,硫酸锌对黄铜矿和方铅矿浮选的抑制作用减弱;硫酸锌、低用量硫酸铜、亚硫酸钠或硫化钠对闪锌矿浮选以及硫酸铜对黄铜矿和方铅矿浮选的抑制作用更强;硫酸锌或硫酸铜对黄铁矿浮选以及较高用量硫酸铜对闪锌矿浮选的活化作用相当;亚硫酸钠或硫化钠对黄铜矿、方铅矿和黄铁矿浮选的影响很小。研究结果可为部分硫化矿通过改变调整剂与捕收剂的加药顺序提高矿物浮选分离效率提供借鉴。