Flotation pyrite

Dichmann, T. K. Finch, J. A. The role of copper ions in sphalerite—pyrite flotation selectivity. Miner. Eng. 2001, 14, 217-225. 

Arsenical gold ores that do not contain significant base metals are treated using a bulk flotation method, where all the sulphides are first recovered into a bulk concentrate. In case the gold is contained either in pyrite or arsenopyrite, separation of pyrite and arsenopyrite is practiced. There are two commercial methods available. The first method utilizes arsenopyrite depression and pyrite flotation, and consists of the following steps ... 

The soluble complexes formed by activators will desorb cation from the lime depressed pyrite surface, which will expose a fresh pyrite surface and activate pyrite flotation. Therefore, the moderately strong acids such as oxalic acid and phosphoric acid exhibit a strong activation action on lime-depressed pyrite because of their ability to decrease pulp pH and to form soluble complexes with hydrated surface cations. 

Baldauf, H. and Schubert, H., 1980. Fine Particles Processing, 1(39) 767 - 786 Ball, B. and Richard, R. S., 1976. The chemistry of pyrite flotation and depression. In Flotation, A. M. Gaudin Memorial volume, M. C. Fuerstanau(eds.), AIME, Inc., 1 458 - 484 Basiollio, C., Pritzker, M. D., Yoon, R. H., 1985. Thermodynamics, electrochemistry and flotation of the chalcocite-potassium ethyl xanthate system. SME-AIME Annual Meeting, New York, Preprint No. 85 - 86... 

Bulut, G. and Atak, S., 2002. Role of dixanthogen on pyrite flotation solubility, adsorption studies and E h. FTIR measurements. Minerals Metallurgical Processing, 19(2) 81-86 Cases, J. M., Kongolo, M., de Donato, P., Michot, L. and Eire, R., 1990. Interaction between firely ground galena and pyrite with potassium amylxanthate in relation to flotation, 2. Influence of grinding media at natural pH. Inter. J. Miner. Process, 30 35 - 67... 

Hu Yuehua, Dai Jingping, Zhang Qin, 2004. Electrochemical flotation of diethyldithiocarbamate-pyrrhotite system. J. Cent. South Univ. Technol., 11(3) 270 - 274 Janetski, N. D., Woodbum, S. I., Woods, R., 1977. An electrochemical investigation of pyrite flotation and depression. Inter. J. Miner. Process, 4 227 - 239 Jellinek, F., Poliak, R. A., Shafer, M. W., 1974. X-Ray photoelectron spectra and electronic structure of zirconium trisulphide and triselenide. Materials Research Bulletin, 9(6) 845-856... 

Fig. 14. Coal flotation flow sheet suggested for increased sulfur removal (29). Pyritic sulfur removal from coal makes it imperative to closely control pulp...

Depressants are reagents that selectively prevent the reaction between a coUector and a mineral, thus preventing its flotation. For example, sodium cyanide [143-33-9] depresses sphalerite [12169-28-7] (zinc sulfide) and pyrite [1309-36-0] (iron sulfide) but not galena. It thus enhances selective flotation of the galena. 

Biological processes are also being studied to investigate abiHty to remove sulfur species in order to remove potential contributors to acid rain (see Air pollution). These species include benzothiophene-type materials, which are the most difficult to remove chemically, as weU as pyritic material. The pyrite may be treated to enhance the abiHty of flotation processes to separate the mineral from the combustible parts of the coal. Genetic engineering (qv) techniques are being appHed to develop more effective species. 

Flotation. The appfication of flotation (qv) to coal cleaning is a relatively new development iu the United States. In 1960, only 0.6% of the clean coal produced came from flotation. However, by 1983 flotation accounted for about 5% of the clean coal production (Table 2). Utilization of the flotation process is expected to grow rapidly because more fine size coal is produced as a result of beneficiation schemes that require significant size reduction of the taw coal prior to cleaning to enhance the fiberation of pyrite and ash minerals. 

The KEN-FLOTE column (11) is one of several column flotation processes based on a countercurrent principle. The feed slurry containing reagents is iatroduced iato the column just below the froth zone. Air is iujected at the bottom of the column via an air sparger. Wash water is sprayed within the froth zone to reject the entrained impurities from the froth. Test results on this column iadicate that a 6% ash product coal having a combustible-recovery of 75—80% can be obtained. A 70—80% pyrite reduction is also claimed. Figure 2 shows the operation of such a column. 

The pH of the pulp to the flotation cells is carefliUy controlled by the addition of lime, which optimizes the action of all reagents and is used to depress pyrite. A frother, such as pine oil or a long-chain alcohol, is added to produce the froth, an important part of the flotation process. The ore minerals, coated with an oily collected layer, are hydrophobic and collect on the air bubbles the desired minerals float while the gangue sinks. Typical collectors are xanthates, dithiophosphates, or xanthate derivatives, whereas typical depressants are calcium or sodium cyanide [143-33-9] NaCN, andlime. 

A U.S. Bureau of Mines survey covering 202 froth flotation plants in the United States showed that 198 million tons of material were treated by flotation in 1960 to recover 20 million tons of concentrates which contained approximately 1 billion in recoverable products. Most of the worlds copper, lead, zinc, molybdenum, and nickel are produced from ores that are concentrated first by flotation. In addition, flotation is commonly used for the recoveiy of fine coal and for the concentration of a wide range of mineral commodities including fluorspar, barite, glass sand, iron oxide, pyrite, manganese ore, clay, feldspar, mica, sponumene, bastnaesite, calcite, garnet, kyanite, and talc. 

In an extensive study by Read et al. [93], 10 anionic surfactants were evaluated for their ability to remove pyritic sulfur and ash from ultrafine Illinois no. 5 coal by flotation processes. The authors observed that of the commercially available surfactants, sodium dodecyl sulfate was the most effective on either a weight or a molar basis, followed by a linear AOS (average molweight 272) and alkylpolyethoxylated sulfonates. Of the noncommercial surfactants tested, -(E -b-dodecene-b-suIfonate (f0) was the most effective and better than any commercial surfactant on a dosage/recovery basis. 

Flotation of arsenical gold ores associated with base metals is accomplished using a sequential flotation technique, with flotation of base metals followed by flotation of gold-containing pyrite/arsenopyrite. The pyrite/arsenopyrite is floated at a weakly acid pH with a xanthate collector. 

Flotation of pyrite using either ethyl xanthate or potassium butyl xanthate as collector. Glycol frother is also usually employed in this separation. 

The second method involves depression of pyrite and flotation of arsenopyrite. In this method, the bulk concentrate is treated with high dosages of lime (i.e. pH> 12), followed... 

Flotation of gold-bearing sulphides from ores containing base metal sulphides present many challenges and should be viewed as flotation of the particular mineral that contains gold (i.e. pyrite, arsenopyrite, copper, etc.), because gold is usually associated with these minerals at micron size. 

Most of the current commercial operations that treat PGM from sulphide-dominated deposits are located in South Africa (Morensky Reef), Stillwater mines (Montana, USA) and Lac des Hies (Ontario, Canada). From a processing point of view, most of these ore types contain hydrophobic gangue minerals, including talc, which has a negative effect on PGM recoveries. Other major factor that affects flotation recovery of PGM is the presence of a variety of sulphide minerals, including pyrrhotite, pentlandite, chalcopyrite, violarite and pyrite, where... 

Each of the sulphide minerals, which are PGM carriers (i.e. pyrrhotite, pyrite, pentlan-dite, etc.) have different flotation properties under some flotation conditions. The selectivity between sulphide minerals and gangue minerals is relatively poor in principle, and in the majority of cases, a hydrophobic gangue depressant has to be used. 

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