Reverse flotation

The reverse flotation method. It was examined by several Russian scientists. This method involves depression of smithsonite using sodium phosphate and dextrin. Calcite and dolomite are floated using oleic acid in stage additions. The tailings become the zinc concentrate. 

Jiang Hao, Hu Yuehua, Xu Jing, 2000. Electrochemical characteristics of couple electrode of galena-pyrite in different solutions. Trans. Nonferrous Met. Soc. China, 10 87 - 88 Johnson, N. W. and Munro, P. D., 1988. h-pH measurements for problem solving in a zinc reverse flotation process. Austral Inst. Min. Metall., 239(3) 53 - 58 Karkovsky, I. A., 1957. Physicochemical properties of some flotation reagents and their salts with ions of heavy iron-ferrous metals. Proc. 2nd Int. Congr. Surface Activity, London, 4 225 - 237... 

Froth flotation has proven to be an efficient method of removing titaniferous impurities (mainly iron-rich anatase) from kaolin clays. Fatty acid reagent, primarily tall oil, is used extensively in the reverse flotation of these impurities. This flotation collector typically requires divalent cations (usually Ca +) to activate the coloured impurities and enhance collector adsorption. This is not very selective since the tall oil can also absorb on the kaolinite particles. Alkyl hydroxamate collectors are relatively new in the kaolin industry but provide significant advantages. Hydroxamates do not require activators, substantially increase the removal of colored impurities and are very selective. 

Depending on the characteristics of the coal to be processed, Bechtel s unit has the flexibility to be operated in a number of modes. One such mode of operation involves a 3-stage, "reverse" flotation process. In this case, clean coal will be floated in the first two stages. In the final, or reverse-flotation, stage the clean coal product will be conditioned with reagents so that pyrite particles will float to the surface, and the clean coal will sink to the bottom of the cell, where it is collected as the final product. 

The problem of solvation of dextrins is still unsolved in general. It was documented that even such commonly used solvents as ethanol exhibit an unusually strong interaction with dextrin, as determined by H-n.m.r. spectroscopy. The interaction of dextrin with normal alcohols from methanol to 1 -hexanol was studied by determination of their infinite-dilution activity-coefficients in dextrin - water mixtures. " Studies carried out on the adsorption of dextrin on oxidized coal revealed that hydrophobic moieties in dextrin are involved in that process. The possibility of hydrophobic bonding has made dextrin an interesting component of the media used for flotation. Dextrin acts as a flocculant (depressant). When combined with a proper additive providing action by means of hydrogen bonding, reverse flotation... 

Various starches have been used in industry for depressing talc, mica, natural sulfur, carbon gangue and sulfide minerals, and especially for depressing oxidized iron minerals in the reverse flotation of iron ore and the separation of Cu-Mo in the copper-molybdenite sulfide flotation. 

Tannins are mainly used as depressants for dolomite, calcite and silicate minerals in the flotation of scheelite, apatite, fluorite and copper sulfide. Like starch, tannins after modification by oxidation, sulfidization and aminization (tannin O, S and A, respectively) have been used as a depressant for hematite in the reverse flotation of quartz with oleic acid or dodecylamine as collectors [22]. Flotation results show quartz to be depressed by tannins in the order of tannin A > S at low concentrations of dodecylamine. When an anionic collector is used for the reverse flotation of Ca +-activated quartz with tannins as depressant for hematite, the order of depression is tannin A > O > S. 

Selective flotation of fluorite and barite is usually very difficult using water glass and tannic acid. However, good separation of these minerals has been achieved with the use of lignosulfonate [18]. Lignosulfonate can also selectively depress molybdenite and some rare earth metal minerals. In the reverse flotation of hematite and quartz, lignosulfonate has been used as a depressant of hematite. 

Quartz Fatty acids, a mitres Fatly acids, amines Stanch, dextrin Flotation of bemetite using fatty acids around anutral pH and reverse flotation of quartz using amines Easily flotable in tbe acidic range calcite is usually present as ihe gargue in other salt-type minerals... 

The reduction of sulfur is one of the principal benefits of the froth flotation process. Of the two types of sulfur in coal (i.e., inorganic and organic), only the inorganic sulfur (mainly represented by pyrite) can be separated fi om coal by physical methods. The floatability of coal-pyrite is, however, somewhat different fi om that of ore-pyrite, and its separation from coal presents a difiicult problem. The research based on the behavior of ore-pyrite in the flotation process— namely, its poor flotability under alkaline conditions—did not result in a development of a coal-pyrite selective flotation process. The two-stage reverse flotation process proved to be much more successful. In... 

The reverse flotation of halite is preferable when KCl is in the form of carnallite (KCl.MgCl.6H2O). Traditional direct flotation of sylvite (KCl) with fatty amines will not work with carnallite ores. From carnallite, it is possible to produce pure KCl and MgCl2 by using... 

Petroleum sulfonate was used to directly flotate the raw ore in laboratory. Meanwhile, fatty acid was used to reversely flotate quartz in the flotation of the raw ore. Comparison between direct and reverse flotation separations is given as follows ... 

Direct flotation with petroleum sulfonate Quartz reverse flotation with fatty acid ... 

These amine collectors include Alamine, Alamac, Armac, Armeen, and Ninol in other countries. Amine collectors are mainly used to flotate quartz, aluminosilicate, phosphate, carbonate, and soluble salt. Meanwhile, they can be applied in the reverse flotation of hematite. 

In recent years, fatty amines have been used as the collector of quartz in the reverse flotation of hematite in laboratory and industry. For example, using starch and dextrine as depressant, the flotation results of Canadian Knob iron ore using various amine collectors in laboratory can be given as follows ... 

According to the report of lU. G. Pukin, salamide can be used as the depressant of feldspar in the flotation of tantalum niobium. Sulfosalicylic acid and alizarin red can depress the valuable mineral to achieve the reverse flotation of feldspar in the separation of spodumene and tantalum niobium. 

Tannin can also be used as the depressant of hematite in the reverse flotation of quartz activated by Ca " using anionic collector. 

Lignosulfonate can also be used as the depressant of hematite in the reverse flotation of quartz activated by Ca " using anionic collector. According to the report of T.O. Hisco, Lignosulfonate can also be used as the depressant of chalcocite in the flotation separation of Cu-Mo ore. 

The structure and performance of starch had been discussed in the former Chapters. Based on the flotation application of starch, starch is mainly used to depress hematite in the reverse flotation process. In addition, starch depressants are also applied in the flotation separation of Cu-Mo ore [7, 8]. The modified products of starch can selectively depress quartz, silicate, and talcum. 

WangQiuLin, An Experimental Research on Roasting-magnetic Separation-Reverse Flotation of Oolite Hematite fiom Exi Iron Ore,"HuNan Nonferrous Metals, 25 (2009), 12-15... 

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