Exploiting the dual functions of polymer depressants in fine particle flotation

Fine hydrophilic particles are known to be entrained with water in flotation of many ores. Flocculation of the hydrophilic particles by polymer depressants could potentially reduce the mechanical entrainment of these particles. This paper reports testwork completed on fine particles of several solids, iron oxide, hydroxyapatite and sphalerite, as well as on a relatively coarse quartz sample (− 75 + 38 μm). Dodecylamine was used as a collector for quartz, and several dispersants and polymer depressants, including sodium silicate, sodium metaphosphate, zinc sulfate, cornstarch, corn dextrin and carboxymethyl celluloses (with molecular weights of both 700,000 and 80,000) were used as flotation modifiers. The major part of the testwork involved flotation tests in a 200 mL flotation column. It was observed that flocculation of the fine hydrophilic particles significantly reduced their mechanical entrainment, while dispersion severely aggravated it. Thus, in the flotation separation of synthetic mixtures of the − 75 + 38 μm quartz and fine (reagent grade) iron oxide or hydroxyapatite, polymer depressants that caused flocculation performed better than those that did not cause flocculation.     

国内外“人工矿床”研究现状与前景

“人工矿床”主要是指废石及尾矿等能被重新利用的资源，在富矿资源日益减少的今天，贫矿资源，废石及尾矿等非传统资源的开发利用越来越受到重视，目前，国内外主要从物质再回收和物质转移两个方面对废石和尾矿的综合利用进行研究。国外已利用细菌浸出等先进的矿物加工工艺从低品位的含铜和含金的废石和尾矿中回民铜和金，利用已无回收价值的尾矿加工制造水泥，陶瓷，玻璃等新型材料，国内主要利用重选，磁选，浮选，化学选矿联合工艺流程回民铁，铜，金等尾矿中的有用元素,利用废石，尾矿作建筑石料或加工制造砖，混凝土，陶瓷等建筑材料。     

Flotation study on high-hercynite ilmenite ores

Ilmenite from Polish magnetite-ilmenite ores has been floated with tall oil. Chemical and mineralogical analysis of the flotation products established that the ores containing hercynite are difficult to upgrade. For ore A (18.7% hercynite and 32.8% ilmenite) and ore B (9% hercynite and 41.3% ilmenite) poor concentrates containing much less than the required 45% TiO₂ have been obtained. It has been found that the higher concentration of hercynite in the feed, the lower the grade of concentrates in respect to TiO₂ is obtained. Ilmenite ore containing a minor amount of hercynite (ore C, 0.15% hercynite and 12.3 ilmenite) gives a good concentrate. By means of microscopic observation it was established that hercynite floats together with ilmenite in the rougher flotation but is partially depressed in the cleaning and scavenging flotation.     

The effect of slime coatings of the serpentine minerals,chrysotile and lizardite,on pentlandite flotation

Serpentine minerals in the gangue often interfere with the concentration of nickel sulfide ores. The influence of slime coatings of the serpentine minerals chrysotile and lizardite on the flotation of unoxidized pentlandite has been studied. In addition to microflotation testing at pH 9 with potassium amyl xanthate collector, electrophoresis and scanning electron microscopy have been used. The formation of a slime coating was found to be directly related to the surface charges on the slime and the sulfide mineral. Chemical additives which modified the slime surface charge, such as carboxy methyl cellulose, dextrin, sodium pyrophosphate and sodium silicate, were shown to be effective in reducing the adverse influence of the slime on the flotation of pentlandite.     

石英与钠长石浮选分离的研究

用十八胺(阳离子捕收剂)和十二烷基磺酸钠(阴离子捕收剂,SDS)作浮选为捕收剂分离石英与钠长石,研究了浮选条件对分离效果的影响以及捕收剂在矿物表面的吸附行为.结果表明,最佳浮选条件是浮选液的pH=2,阴、阳离子捕收剂的浓度分别为3.0×10-6 mol/L和4.0×10-6 mol/L;阴阳离子捕收剂在石英与钠长石两种矿物上表现出相同的吸附行为.在最佳浮选条件下,对不同配比的石英和钠长石混合物进行浮选,石英回收率为14%,钠长石回收率达80%,分离效果显著;对含微量长石的石英矿粉进行浮选,分离效果与石英与钠长石混合物相近.     

新型捕收剂RA-92在低品位碳酸锰矿选矿中的应用

微细粒低品位锰矿由于颗粒间的非选择性聚集、浮选药剂用量大、浮选效率低等技术难题而致使其利用困难,造成大量浪费。在品位低于13%的锰矿浮选技术研究中,捕收剂最受关注,前人已研究了多种类型的捕收剂,所得精矿品位在16.9%~18.3%之间,回收率为56%~97%,回收率比较理想,但精矿品位总体不高。本文将新型捕收剂RA-92应用于湖南凤凰-花垣地区低品位碳酸锰矿(锰品位为10.7%)的选矿工艺中,实验研究了磨矿细度、pH值、抑制剂和捕收剂用量对浮选效果的影响,在最佳工艺条件下,精矿品位由原矿的10.7%提升至17.4%,回收率达到80.2%。研究表明RA-92对碳酸锰矿具有良好的捕收性能,浮选工艺相对简单且捕收剂用量少,浮选成本较低,可为此种捕获剂在微细粒低品位碳酸盐锰矿选矿中的应用得到推广。     

The anomalous behavior of kaolinite flotation with dodecyl amine collector as explained from crystal structure considerations

The electrokinetics and flotation behavior of kaolinite have been investigated through flotation experiments, zeta potential measurements, and FTIR spectral analysis. These results have been explained based on crystal structure considerations and quantum mechanical calculations. It has been shown that the PZC of kaolinite is at pH 4.2. Kaolinite exhibits good floatability in weakly acidic solution with dodecyl amine (DDA) collector. The negative zeta potential of kaolinite increases with an increase in pH, and hence the adsorption of DDA on kaolinite increases. However, the flotation of kaolinite decreases with an increase in pH and an increase in DDA adsorption. This anomalous flotation behavior is rationalized based on crystal structure considerations and particle aggregation phenomena. It is considered that the silica (001) and the alumina (001¯) basal planes of kaolinite are negatively charged. From quantum chemistry calculations, the interaction between DDA and the (001) plane was found to be stronger than at the (001¯) alumina plane due to the difference in the structure at the (001) and (001¯) planes. The self-aggregation between (001¯) faces and the edge planes and the adsorption of DDA at the silica (001) plane make the kaolinite aggregates hydrophobic, and good floatability is achieved in acidic solution. In alkaline solution, the kaolinite particles are dispersed. In the presence of DDA, hydrophobic aggregation appears to occur in alkaline solution between the (001) planes due to adsorbed DDA, and thus the hydrophilic (001¯) faces are exposed and flotation is not achieved.     

混合捕收剂去除高岭土中含铁矿物试验研究

文章根据高岭土中含铁矿物的浮选试验研究,采用胺类与皂化油酸表面活性剂组合作为高岭土中含铁矿物的捕收剂。高岭土中铁的赋存状态表明,采用分段阳离子/阴离子捕收剂组合试剂,当pH=8～10时,十八胺乳化液以静电力吸附形式捕收含铁硅酸盐;当pH=5～7时,皂化油酸和少量十二烷基磺酸钠通过表面活化反应捕收氧化铁矿,使北海高岭土精矿自然白度达到85%～86%,煅烧白度（1 200℃）达到88%～89%。     

Inorganic arsenic sorption by drinking-water treatment residual-amended sandy soil: effect of soil solution chemistry

Previous studies in our laboratory have demonstrated that drinking-water treatment residuals are effective sorbents of arsenic V. However, the effect of soil solution chemistry on arsenic V sorption by drinking-water treatment residuals-amended soils remains to be explored. The current study uses a batch incubation experimental set up to evaluate the effect of soil solution pH, competing ligands, and complexing metal on arsenic V sorption by a sandy soil (Immokalee series) amended with two rates (25 and 50 g kg^?1) of aluminum and iron-based drinking-water treatment residuals. Experiments were conducted at three initial arsenic loads (125, 1,875, 3,750 mg kg^?1) and a constant solid: solution ratio of 200 g L^?1. An optimum equilibration time of 8 days, obtained from kinetic studies, was utilized for sorption experiments with both aluminum and iron drinking-water treatment residual-amended soil. Presence of phosphate decreased arsenic V sorption by both aluminum and iron drinking-water treatment residual amended soils, with a strong dependence on pH, drinking-water treatment residual types, drinking-water treatment residual application rates, and phosphate concentrations. Addition of sulfate had no effect on arsenic V sorption by aluminum or iron drinking-water treatment residual-amended soil. A complementing effect of calcium on arsenic V sorption was observed at higher pH. Results elucidating the effect of soil solution chemistry on the arsenic V sorption will be helpful in calibrating drinking-water treatment residual as a sorbent for remediation of arsenic-contaminated soils.     

Flotation of oxidized minerals of copper using a new synthetic chelating reagent as collector

A new synthetic reagent containing a mixed aliphatic-aromatic structure, with a hydrocarbon chain and an aminothiophenol chelating group, has proven to be an effective collector for the flotation of chrysocolla minerals. The flotation is optimum in the narrow pH range of 5.5 to 6, falls sharply at pH 5, and is moderate in the pH range 7 to 11. Infrared spectra indicate that copper aminothiophenolate chelates are formed on the surface of the chrysocolla under the conditions of maximum flotation.     

Flotation of fluorite with n-alkylammonium chlorides

Experimental study on the electrokinetic and flotation behaviour of fluorite in solutions of n-alkylammonium chlorides (with 10, 12 and 14 carbon atoms) is given. The zero point of charge (ZPC) of luorite was determined by measuring zeta potential (streaming potential method) as a function of pH. Two conditioning times of the mineral with the solution were used (10 minutes and 48 hours) and the respective ZPC were located at pH 2.2 and 8.4. Decyl-, dodecyl- and tetradecylammonium ions seem to be strongly adsorbed on the interface because they made the zeta potential more positive as the concentration increases. Hallimond tube flotation of fluorite was studied and shown to be influenced by the chain length of the collector and both collector and hydrogen ion concentrations. Flotation recovery for a given concentration of collector increases with the number of carbon atoms of the chain. The results have been discussed in the light of the electrical double-layer theory.     

贵州省兴义市雄武地区金矿石堆浸的工艺研究

贵州省兴义市雄武地区金矿主要为卡林型,其次为红土型,矿床受断裂构造控制,矿石为中等含硫微细浸染状氧化矿石。目前浅部矿石已基本采完,深部矿石品位较低(0.8~1.8 g/t),因此有效提高低品位矿石浸出率和金回收率至关重要。研究表明,筑堆时矿石粒度和喷淋时氰化钠浓度是堆浸生产中的重要影响因素。矿石粒度大,金浸出率低;氰化钠浓度大,则成本增加。根据矿石物质成分和工艺特征研究,得到矿石冶炼时的最佳工艺条件:筑堆时矿石粒度为15~25 mm,氰化钠浓度为0.05%~0.08%。该研究有效提高了矿石浸出率,降低了运营成本,为金矿石堆浸实际生产提供了理论和实验依据。     

Flotation of calcareous Mussorie phosphate ore

Separation of Mussorie rock phosphate (P₂O₅ = 20%) from Uttar Pradesh, India, containing pyrite, calcite and other carbonaceous impurities by flotation has been successfully attempted to upgrade the phosphate values. Based on Hallimond cell flotation results of single and synthetic mineral mixtures of calcite and apatite using oleic acid and potassium phosphate, conditions were obtained for the separation of calcite from apatite which is considered to be the most difficult step in the beneficiation of calcareous phosphates. Further studies using 250 g of the mineral (?60 +150 and ?150 mesh fractions, deslimed) in laboratory size Fagergren subaeration machine employed a stagewise flotation viz. carbonaceous materials using terpineol, pyrite using potassium-ethyl xanthate and calcite using oleic acid respectively. Separation was, however, found to be unsatisfactory in the absence of a depressant.Among starch, hydrofluosilicic acid and dipotassium hydrogen phosphate, which were tried as depressants for apatite in the final flotation stage, dipotassium hydrogen phosphate proved to be superior to others. However, the tests with the above fractions did not yield the required grade. This was possibly due to insufficient liberation of the phosphate mineral from the ore body and different experimental conditions due to scale up operations. Experiments conducted using ?200 mesh deslimed fractions has yielded an acceptable grade of 27.6% P₂O₅ with a recovery of about 60%. The results have been explained in terms of the specific adsorption characteristics of phosphate ions on apatite and the liberation size of the mineral.     

苏丹东部地区BIF型铁矿和CID型铁矿的发现及其找矿意义

在苏丹东部地区新元古代地层中,新发现的BIF铁矿是与火山岩密切相关的Algoma型铁矿,矿石品位TFe 37.78%,对进一步研究努比亚地盾的形成时代和古地理环境有一定的参考意义。苏丹79区块发现的含铁石英砂岩,呈北东向带状分布, 角度不整合于努比亚地盾之上,通过与西澳CID型铁矿对比,存在交错层理和底砾岩等明显的再生沉积特征,矿石品位TFe 31.91%～39.33%;通过对BIF型铁矿、CID型铁矿和努比亚杂砂岩三者部分元素及氧化物含量的分析对比,以及控矿地质因素分析, CID型铁矿是由BIF铁矿风化剥蚀后搬运沉积于附近古河道内;苏丹努比亚地盾区CID型铁矿的发现,为今后找矿工作提供了新目标,具有十分重要的找矿意义。     

Effect of oxidation potential and zinc sulphate on the separation of chalcopyrite from pyrite

The effects of oxidation potential (Eh) and zinc sulphate on the separation of chalcopyrite from pyrite were investigated at pH 9.0. The flotation recovery of these minerals is Eh dependent with maximum separation obtained at 275 mV SHE. Zinc sulphate addition improved this mineral separation at an Eh value of 275 mV by selectively depressing pyrite flotation. A different result was obtained at lower Eh values where zinc sulphate addition improved chalcopyrite flotation but had no or little effect on pyrite flotation. These opposite effects of zinc sulphate on mineral flotation were reconciled by examining the surface species of these minerals. The selective depression of pyrite flotation by zinc sulphate was also confirmed in the flotation of two copper ores.     

Upgrading of calcareous phosphate ores by flotation: Effect of ore characteristics

Sedimentary phosphates contain-besides the phosphate minerals-, various associated gangue minerals such as: clays, silica, calcareous minerals (mainly calcite and dolomite), carbonaceous matter, iron oxides and/or pyrite. The common practiced flow-sheets for concentrating these types of phosphate ores consist of a combination of various mineral processing units such as: crushing and screening, attrition, washing, magnetic separation, and/or flotation. However, none of these combinations was successfully efficient to upgrade the calcareous ores because of the close similarity of the physical properties (density, particle size, particle shape, etc.) as well as the surface physico-chemical properties of the carbonate and phosphate minerals. For the last five decades extensive efforts have been spent to adopt flotation for separating carbonates from phosphate ores. These efforts include thermodynamic analysis, modification of the technique, controlling the pulp environment, and finding new reagents that can specifically differentiate between carbonates and phosphates.This paper reviews some of the published work on the separation of carbonates from phosphate ores by flotation and presents the flotation results of phosphate ore samples different in their physical properties and mineralogical composition. The results obtained reflect the effect of ore nature on the flotation performance and the reagents consumption.     

Zero-valent iron/persulfate(Fe0/PS) oxidation acetaminophen in water

Zero-valent iron (Fe⁰), as an alternative iron source, was evaluated to activate persulfate (PS) to degrade acetaminophen (APAP), a representative pharmaceutically active compound in water. Effects of key factors in the so-called Fe⁰/PS process, including Fe⁰ dosage, initial pH, temperatures and chelating agents, were studied. Under all the conditions tested, the APAP degradation followed a pseudo-first-order kinetics pattern. The degradation efficiency of APAP was highest when the Fe⁰ to PS molar ratio increased to 1:1, and the degradation rate constant and removal were 23.19 × 10^?3 min^?1 and 93.19 %, respectively. Comparing with Fe²⁺, Fe⁰ served as an alternative iron source that can gradually release Fe²⁺ into water, thereby consistently activating PS to produce sulfate radicals. The Fe⁰/PS system was effective in a broader pH range from 3 to 8.5. Heat could facilitate production of sulfate radicals and enhance the APAP degradation in the Fe⁰/PS system. High reaction temperature also improved the Fe²⁺/PS oxidation of APAP. Finally, sodium citrate (a chelating agent) at an appropriate concentration could improve the APAP degradation rate in the Fe²⁺/PS and Fe⁰/PS system. The optimal molar ratio of Fe⁰ to citrate depended on solution pH. Our results demonstrated that Fe⁰ was an alternative iron source to activate PS to degrade APAP in water.     

Soft X-ray spectroscopic studies of the reaction of fractured pyrite surfaces with Cr(VI)-containing aqueous solutions

We have used synchrotron-based soft X-ray core-level photoemission and adsorption spectroscopies to study the reaction of aqueous sodium chromate solutions with freshly fractured pyrite surfaces. Pyrite surfaces were reacted with 50 μM sodium chromate solution at pH 7 for reaction times between 1 min and 37 hr. Additional experiments were performed at pH 2 and pH 4 with 50 μM sodium chromate solutions and at pH 7 with 5 mM solutions. At chromate concentrations of 50 μM, all chromium present on the pyrite surface was in the form of Cr(III), while at 5 mM, both Cr(III) and Cr(VI) were present at the pyrite surface. Minor quantities of oxidized sulfur species (sulfate, sulfite, and zero-valent sulfur) were identified as reaction products on the pyrite surface. The amount of oxidized sulfur species observed on the surface was greater when pyrite was reacted with 5 mM Cr(VI) solutions because the rate of chromium deposition exceeded the rate of dissolution of pyrite oxidation products, effectively trapping Cr(VI) and oxidized sulfur species in an overlayer of iron(III)-containing Cr(III)-hydroxide. This work shows that pyrite, an extremely cheap and readily available waste material, may be suitable for the removal of hexavalent chromium from acidic to circumneutral waste streams. The reduced chromium ultimately forms a coating on the pyrite surface, which passivates the pyrite surface towards further oxidation.     

Development and implementation of a new flowsheet for the flotation of a low grade nickel ore

Low grade nickel ores containing large amounts of serpentine minerals have historically been difficult to process efficiently. The Mt Keith ore was no exception with recoveries in the first five years of operation averaging just 60%.In this research, the factors limiting performance have been identified and a new process has been devised that raises recovery significantly. The process exploits the particle size dependence of nickel sulphide flotation and the different ways that pH change and pulp density influence the response of coarse and fine particles.Implementation of the new process at Mt Keith has raised nickel recovery by 10%. In turn, nickel production has increased by over 6000 t.p.a. and the net present value (NPV) of the operation has increased by over A$300 m. These outcomes illustrate the large commercial benefits that can be gained by understanding particle size effects in flotation.     

Floatability of rare earth phosphors from waste fluorescent lamps

Zeta-potential measurements were made to determine the electric state of phosphor materials on the basis of which a feasibility study could be performed for the use of flotation in the recovery of fine (d₅₀ < 13 μm) rare earth phosphors from waste fluorescent lamps. Tests were carried out with pure specimens of white (calcium halo-phosphate), red, green and blue (rare earth) phosphors, with a 17 : 1 : 1 : 1 ratio of their mixture, and with actual waste phosphor materials. The effects of a cationic (dodecyl ammonium acetate, DAA) and two anionic (sodium dodecyl sulfate (SDS) and sodium oleate (NaOl)) collectors on the floatability of materials, as well as that of Na₂SiO₃ dispersant on the separation characteristics, were investigated at different pH ranges. The process, applied to actual discarded waste phosphors gave, in a two-stage separation scheme, sink products assaying 17.7–23.8% and 21.5–25.9% rare earth phosphors for DAA and SDS flotation, respectively. The recovery and Newton's efficiency were about 70–90% and 0.26–0.37, 66–82% and 0.18–0.20, respectively for DAA and SDS flotation.