某金矿洗矿矿泥可选性试验研究

某金矿生产流程中存在大量矿泥,矿泥进入主浮选流程会影响浮选产品品位和金的回收率。对样品进行粒度分析和金属分布率分析发现,矿泥中-400目含量为96.23%,属微细粒矿物,该粒级中金的占有率达到了96.75%。试验中,采用水玻璃对矿泥进行抑制,用捕金灵与丁铵黑药为捕收剂进行浮选,获得了产率为2.38%,品位为32.55g/t,回收率为68.79%的金精矿,尾矿中金品位为0.36g/t。     

Effect of slurry rheology on gas dispersion in a pilot-scale mechanical flotation cell

This paper investigates the effect of slurry rheology on gas dispersion in a 100 l pilot-scale Batequip mechanical flotation cell. The study is conducted using Kaolin, Bindura nickel and Platreef slurries. All three ores display typical non-Newtonian rheological behaviour. The slurry yield stress and viscosity increase exponentially with solids concentration. Bubble size and gas hold-up vary from 0.60 to 1.10 mm and 2% to 15%, respectively. At low/moderate solids concentrations, bubble size and gas holdup display characteristic trends, as noted in numerous literature studies. At high solids concentrations, both bubble size and gas holdup decrease significantly, which is an unexpected finding. This is attributed to the formation of a ‘cavern’ of slurry around the impeller, due to the very high slurry yield stresses. This ‘cavern’ results in the generation of small bubbles in the impeller zone, but poor dispersion of these bubbles throughout the cell, resulting in low gas hold-ups.     

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 sea water on copper and gold flotation in the presence of bentonite

In this study, the flotation of a copper–gold ore in the presence of 10% bentonite in tap water and sea water was investigated. It was found that bentonite had a deleterious effect on copper and gold flotation in tap water, but this deleterious effect was mitigated in sea water. Rheology measurements, settling tests and Cryo-SEM analyses were conducted to understand the underpinning mechanism. It appears that the high viscosity produced by bentonite due to its swelling capacity and cross-linked network structures negatively affected flotation hydrodynamics and therefore copper and gold flotation in tap water. It is interesting that sea water reduced the swelling capacity of bentonite and modified the association modes of bentonite platelets in flotation pulp, resulting in the breakup of links between the structures with relatively large pores, which contributed to the improvement of copper and gold flotation.     

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.     

动力煤选煤厂煤泥浮选降灰提质增效试验研究

高剪切调浆作为煤泥浮选预处理技术,对浮选过程强化具有积极作用。本次研究以内蒙古自治区鄂尔多斯市乌审旗图克镇葫芦素煤矿的煤样进行一系列的调浆浮选实验,研究了高剪切调浆预处理对于该煤样浮选的影响。结果表明：FDJ+Q1药剂组合下,高剪切调浆浮选比常规浮选可燃体回收率提高了3.79个百分点;在可燃体回收率相近的情况下,可节省捕收剂用量37.5%;浮选动力学实验结果表明,经过高剪切调浆预处理,前两个20 s内可燃体回收率分别提升了20.02%和25.99%,90 s时基本完成分选过程,浮选速度常数增大了近50%。EKOF+仲辛醇药剂组合下,高剪切调浆强大的剪切力与涡流效应会使复合药剂中的起泡剂在调浆阶段便发挥作用,气泡携带煤粒上浮,并带走未及时分散的药剂,造成药剂的浪费,恶化浮选效果。     

The influence of particle shape properties and associated surface chemistry on the flotation kinetics of chalcopyrite

The role of particle shape properties in determining flotation kinetics was investigated in this study. −150/+75 μm chalcopyrite was floated in a microflotation cell, and shape properties of the timed concentrates were quantified using a mineral liberation analyser - a mineralogical characterisation system based on automated scanning electron microscopy. It was found that, when floated in the absence of collector, particles with angular shape features reported to the concentrate faster than round particles. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) showed that angular particles also exhibited surface chemistry characteristics favourable for flotation. When particle floatabilities were high (i.e. when floated in the presence of potassium amyl xanthate), shape properties were not found to contribute significantly to the rates at which particles floated.     

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.     

The effect of the reagent suite on froth stability in laboratory scale batch flotation tests

In batch flotation tests conducted on ores from the Merensky reef, changes in froth stability invariably occur with variations in the reagent suite. The main reagents are collectors (primary and secondary), activators, depressants and frothers. Since the particles entering and leaving the froth in a batch flotation system are continuously changing, the stability of the froth can vary. Under these conditions the simplest measure of froth stability is the measure of water recovery at a fixed froth height. The batch flotation system developed at UCT allows for the separation of gangue which is entrained relative to gangue which is floated. It has been found that the presence of naturally floatable gangue (NFG) leads to froth stabilisation, whereas the presence of hydrophobic sulfide minerals may lead to destabilisation of the froth depending on the hydrophobicity (contact angle) of the sulfide minerals. This can vary with ore type since particle shape and amount of particles present can influence the extent of destabilisation. At low depressant dosages sodium isobutyl xanthate (SIBX) always results in lower froth stability than sodium ethyl xanthate (SEX). The frothing nature of dithiophosphate leads to increased froth stability and the addition of copper sulfate results in destabilised froths. Increasing depressant dosage reduces the stabilising influence of NFG and the depressant type (guar gum or CMC) also affects froth stability. Frother can be used in an attempt to overcome the destabilising effects of high depressant dosage. This work examines the effect of variations in the reagent suite and uses water recovered at a fixed froth height as an indication of froth stability in order to analyse these effects on the recovery of sulfide minerals, floatable gangue and entrained gangue.     

Predicting the surface chemistry contribution to the flotation recovery of chalcopyrite by ToF-SIMS

In flotation, the surface chemistry of the minerals plays a crucial role in the selectivity and recovery of valuable minerals. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) surface analysis is used in this study to investigate the impact of surface chemistry on the flotation of chalcopyrite with dithiophosphate collector. The ToF-SIMS data corresponding to concentrate and tail particles were statistically analysed employing a combination of multivariate statistical techniques - principal components analysis and discriminant analysis - to identify the surface species that are differential in the flotation of chalcopyrite. Two models were developed to predict the concentrate and tail deportment of particles, one targeting fine and intermediate particle sizes and the other for the coarse particle size. These models were tested using cross-validation and the results showed good prediction accuracy, 88% for fine and intermediate particles and 77% for coarse particles. The models were further tested on feed samples and the results show the developed models can be used as a predictive tool that estimates the maximum recovery expected based on the surface chemistry of particles, as evidenced by ToF-SIMS, under given hydrodynamic conditions.     

Effect of clay minerals on pulp rheology and the flotation of copper and gold minerals

In this study, the effect of bentonite and kaolinite minerals with low and high crystallinity on pulp rheology and the flotation of copper and gold minerals was investigated. It was found that clay minerals modified the pulp rheology depending on the type of clay minerals present. Bentonite, a 2:1 structured clay mineral increased pulp viscosity more significantly than kaolinite, a 1:1 structured clay mineral, and poorly crystallized kaolinite increased pulp viscosity more than well crystallized kaolinite. It was also found that pulp rheology modified by clay minerals was strongly correlated with copper and gold flotation. The higher pulp viscosity corresponded to the lower copper recovery. While high pulp viscosity was related to the decreased gold flotation, slightly increased pulp viscosity by clay minerals enhanced gold flotation.     

Behaviour of swelling clays versus non-swelling clays in flotation

The deleterious effects of clays on flotation performance are widely acknowledged but the mechanisms involved are not clearly established. Moreover, the concentrations beyond which clay minerals become problematic are not clearly defined. One major parameter is the difference between swelling and non-swelling clays which is evaluated in this study. The ore slurry pulp rheology and froth stability were monitored in the absence and presence of different clay minerals. It was found that swelling clays can adversely affect the flotation performance mainly via adsorbing water which changes the rheology and froth stability, reducing both flotation grade and recovery. Non-swelling clays had a lower effect on the rheology. Kaolinite increases the froth stability and reduces the flotation grade but illite showed the least effect on the flotation performance in this study. The potential mechanisms and critical concentrations are discussed.     

The effect of stirring speed and induction time on flotation

A computational fluid dynamic model has been developed for a modified Denver flotation cell used in laboratory batch tests. The model incorporates fundamental aspects of bubble-particle interactions including bubble-particle collision, attachment and detachment. Model predictions are compared against carefully planned laboratory experiments with narrowly-sized spherical ballotini. Flotation results for different impeller speeds have been obtained for a constant air flow into the cell. The particles have been made hydrophobic by methylation with trimethylchlorosilane. For a given particle size, the results from the model and experimental work indicate that there is an optimum stirring speed that produces a good compromise between attachment and detachment rates in the cell for flotation. For less hydrophobic particles, a lower stirring speed is beneficial in having a longer contact time because of the longer induction time required for attachment.     

The effect of biopolymer dispersants on copper flotation in the presence of kaolinite

In this study, three lignosulfonate-based biopolymers, DP1775, DP1777 and DP1778 with different compositions were examined as dispersants in copper flotation in the presence of kaolinite. While rheological measurements indicated that these biopolymers dispersed the kaolinite aggregates, flotation results revealed that the three biopolymers increased the copper recovery, with a decline in copper grade, which was attributed to an interaction of biopolymers with the frother modifying the froth and enhancing the mechanical entrainment. Two-phase foam characterisation revealed a larger height in the blends of biopolymer and frother, which in turn promoted the mechanical entrainment in flotation. The dispersing and foaming abilities of biopolymers were governed by their structural features such as the content of functional groups, the molecular weight and counterions. This study indicates that when selecting a polymeric dispersant in flotation to deal with clay minerals, its froth property should also be taken into consideration.     

Investigation on the flotation behavior and adsorption mechanism of 3-hexyl-4-amino-1,2,4-triazole-5-thione to chalcopyrite

In this paper, a novel surfactant, 3-hexyl-4-amino-1,2,4-triazole-5-thione (HATT) is first introduced as a collector for chalcopyrite flotation. Its flotation behavior and adsorption mechanism to chalcopyrite has been evaluated by micro-flotation tests, and zeta potential, FTIR spectra and adsorption quantity measurements. The results demonstrate that HATT exhibited excellent flotation performances to chalcopyrite at pH 4–8. The adsorption of HATT on to chalcopyrite agrees well with the pseudo-second-order model and Langmuir isotherm, and is a spontaneously endothermic chemisorption process. FTIR spectra and zeta potential analyses further imply that chalcopyrite might chemisorb HATT by formation of HATT–copper surface complexes.     

Effect of amine and starch dosages on the reverse cationic flotation of an iron ore

In iron ore concentration, reverse cationic flotation of quartz has been successfully employed for particles below 150 μm previously deslimed. Amine and starch are used, respectively, as quartz collector and iron oxides depressant. Understanding the mechanisms of reagents interaction is relevant to improve the separation selectivity, especially for high amine dosages. The term clathrate was used to explain this interaction, meaning a molecular compound in which molecules of one species occupy the empty spaces in the lattice of the other species, resulting in the depression of hydrophobic minerals. Laboratory scale experiments were carried out with itabirite iron ore in three different size ranges. The clathrate formation between molecules of amine and starch may explain the increase of SiO₂ content in the concentrates of the coarse size range (−150 + 45 μm) due to an increase in amine dosage.     

Elimination of the adverse effect of cement filling on the flotation of a nickel ore

In China, most of the nickel sulphide deposit is spatially related to ultrabasic rocks and the cementation filling method is used in the process of mining. However, the cement filling from the mine back fill often gets into the ore and interferes with the pentlandite flotation. In this work, the effect of the cement filling on the flotation performance of a nickel ore was studied and ammonium sulphate was used to eliminate this adverse effect. The flotation result shows that the pentlandite recovery decreased from 87% to 65% with the increase of the content of cement filling from 0% to 8%. The addition of ammonium sulphate was shown to improve the flotation performance of pentlandite that depressed by cement filling. This result points out a problem often encounter in the flotation of a nickel sulphide ore and finds a solution to it.     

A review of the effect of water quality on flotation

As water resources become scarcer and society’s demands to reduce freshwater extraction have increased, mine sites have been increasing water reuse and accessing multiple water sources for mineral processing to save freshwater, particularly in froth flotation. Implementation of either strategy may lead to water quality variation that may impact flotation efficiency. A large number of studies have been carried out to enhance the understanding of water quality variation in flotation. However, these studies tend to be performed on a case by case basis. There is a lack of a framework to put together these existing studies, which makes it difficult to understand the topic comprehensively and therefore difficult to identify gaps and directions for future research. This would eventually hinder the ongoing implementation of water conservation practices and thus lead to more pressure being placed on freshwater. In this paper, a review of the existing studies on water quality variation in flotation is given in three aspects: causes of water quality variation, consequences of water quality variation and solutions for problems caused by water quality variation. Based on the three aspects, a framework was developed, with which these studies were categorized and structured. Organizing literature in this way makes it possible to identify gaps in current research and future research directions.     

旋流静态微泡浮选柱在极难选辉钼矿精选中的应用

河南省三门峡市某钼矿矿石氧化程度高且极易泥化,有用矿物嵌布粒度细,被认为是一种极难分选的矿石。该厂长期以来生产指标都不理想,精矿品位只能达到18%左右,回收率也只能维持在50%左右。为此,笔者采用旋流静态微泡浮选柱对该矿石进行了精选试验研究。结果表明,在不影响总作业回收率的情况下,精矿品位大幅度提高,达40%左右,显示了旋流静态微泡浮选柱在处理细粒难选钼矿方面的优势,也为同类型矿石的处理提供了一种有效的途径。