白钨矿和方解石晶面的断裂键差异及其对矿物解理性质和表面性质的影响

运用Materials Studio软件构建了白钨矿和方解石的晶胞,计算了两种含钙矿物晶体不同晶面的断裂键密度、主要解理面和暴露面上Ca活性质点密度和活性质点的未饱和键密度,并利用计算结果分析了两种矿物的解理性质和表面性质.计算分析表明,白钨矿晶体(001)面、(101)面和(111)面为其常见解理面;方解石晶体(10 (14))面为最常见解理面,(21 (34))面、(01 (18))面为常见暴露面;晶体不同表面Ca质点的未饱和键密度大小顺序分别为:白钨矿(101)≥(111)>(001),方解石(21 (34))>(01 (18))>(10 (14)).研究表明,表面Ca质点性质可能是造成两种含钙矿物选择性分离难的关键因素.     

Rejection of arsenic minerals in sulfide flotation — A literature review

Arsenic is one of the most dangerous inorganic pollutants and thus a penalty element in many base metal concentrates. Arsenic removal in sulphide flotation has been studied extensively with various approaches, including pre-oxidation of flotation pulp, E_h control during flotation and the use of selective depressants/collectors. Pre-oxidation of flotation pulp using oxidizing agents or aeration conditioning represents a simple approach in arsenic removal and was found effective in many cases. Selective flotation of arsenic minerals through E_h control has made significant advances in recent years with promising results achieved. In addition, various depressants and collectors have also been studied in arsenic removal. In this communication, the various approaches used in selective flotation of arsenic minerals are reviewed with emphasis on the development in recent years.     

Removal of lead minerals from copper industrial flotation concentrates by xanthate flotation in the presence of dextrin

Potato starch and dextrins resulting from thermolysis of potato starch in the absence of reagents and presence of -amino acids are promising depressants for separation of lead and copper minerals present in the Polish industrial copper concentrates. The polysaccharides were used for differential xanthate flotation of the final industrial concentrates produced by flotation with sulfhydryl collectors in the absence of depressants. The polysaccharides depressed galena and provided froth concentrate rich in chalcocite and other copper minerals as well as cell product containing lead minerals. The best results of separation were obtained in the presence of plain dextrin prepared by a thermal degradation of potato starch. The industrial concentrate containing 18.5% Cu and 5.5% Pb was divided into a froth product containing 38.1% Cu with 77% recovery of copper and a cell product assaying 7.3% Pb with 83% recovery of lead. It was accomplished using 2500 g/t of dextrin, 50g/t of potassium ethyl xanthate, and 50 g/t of frother (α-terpineol). The pH of flotation was 8.0–8.2.     

北祁连块状硫化物矿床中矿石和主要矿石矿物地球化学特征

对北祁连山白银矿田和郭密寺矿田中主要矿床的矿石和矿石矿物组分特征研究表明，由于各矿田的成矿条件和地球化学背景存在差异，造成不同矿床的矿石和矿石矿物元素组合各具特色。但作为同一类型矿床，它们之间又有很多共性，特别是同一矿田内各矿床的地球化学特征具有相似性和过渡性，反映了成矿条件变化的趋势。     

A review of spectroscopic techniques applied to the study of interactions between minerals and reagents in flotation systems

This review article discusses the existing and potential applications of a variety of spectroscopic techniques to determine the interactions between minerals and reagents in flotation systems. To date it is found that infrared spectroscopy is the most successful and the relevant data in the literature is critically evaluated. X-ray photo-electron spectroscopy has also been successfully applied to study mineral—reagent interactions. The potential applications of other spectroscopic techniques (Raman, photo-acoustic, nuclear- and electron-spin resonance, Auger electron, secondary-ion mass spectroscopy, etc.) are also discussed in the above context. The low-surface areas of minerals in flotation systems are a major limitation to the use of some spectroscopic techniques in studying the mineral surface. The suite of reagents used in flotation systems often imposes an additional complicating feature in obtaining relevant spectroscopic data about mineral surfaces. Nevertheless, spectroscopic studies used in the above manner, will continue to give a better understanding of the flotation process.     

The effect of dextrin on surface properties and the flotation of molybdenite

The effect of dextrin on molybdenite surface properties has been investigated experimentally through measurements of zeta potentials, adsorption densities, contact angles, Hallimond tube flotation and oil flotation response. These studies indicate that the adsorption of dextrin on molybdenite occurs through physical interaction with the surface, possibly due to hydrophobic bonding. The hydrophobic bonding mechanism is in accord with the magnitude of the adsorption free energy, which was estimated to be—5.4 kcal per mole of dextrin monomers. Dextrin was found to be a very effective depressant for the air flotation of molybdenite in the absence of a collector, whereas it does not effectively depress molybdenite in an oil flotation process using iso-octane. This has been discussed qualitatively from the contributions of electrical double layer repulsion, van der Waals' attraction, and hydration effects.     

A contribution to physicochemical conditions for the formation of syngenetic sulfide ores

The results of thermodynamic calculations demonstrate that the pH and Eh values for bottom sea water enriched in organic matter tend to decrease drastically as a result of bacterial reduction of sulfates in sea water. Syngenetic sulfide ore beds associated with the Jiashengpan strata-bound Pb-Zn-S ore deposit are believed to have been precipitated under the conditions of pH varying from 7.08 to 7.17 and Eh from −0.232 to −0.418V. It is established that in the reducing system in sea water where reduction of sulfates by anaerobic bacteria took place, paleosalinity is an important factor affecting pH and Eh changes and controlling the formation of sulfide ore beds. The present study shows that the quantitative evaluation of physicochemical conditions can be effected from thermodynamic calculations on the basis of geochemical data.     

A review of the effects of iron redox cycles on smectite properties

The oxidation state of Fe in soils is one of the few properties that can be altered in situ and is known to have a large effect on chemical and physical properties. Understanding this phenomenon enables the possible manipulation or management of the soil in such a way as to maximize the benefit of such changes in properties. The effects of redox cycles, however, are less understood because most studies have focused only on a single reduction event. The purpose of this report is to review the current state of knowledge of the effects of redox cycles on clay and soil behavior, with the hope that this background will encourage further investigations of these processes. Evidence clearly indicates that the means by which reduction of Fe in clay minerals occurs significantly influences the potential reversibility of the process.