Flotation dolomite

Type of gangue minerals - some ore types contain silicate gangue free of slimes, which are the most amenable to flotation. Ores with dolomitic gangue can be beneficiated... 

The flowsheet used to treat dolomitic oxide copper ores is somewhat different from that used in the beneficiation of siliceous oxide copper ores. This is due to the fact that dolomitic ore usually contains elevated amounts of slimes, in which case a split circuit flowsheet has been adopted in a number of operations. The typical flowsheet used for treatment of dolomitic ores is shown in Figure 19.8. Usually, the scavenger tailings are deslimed and the sand fraction is retreated in a scalp copper flotation stage. When the ore is deslimed before flotation, a large amount of fine copper is lost in the slime fraction. 

Fatty acid flotation method. In this method, the smithsonite was floated using a short carbon chain fatty acid from calcific and dolomitic gangue minerals. The calcite and... 

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. 

The treatment process and flotation properties of pyrochlore are very much dependent on the gangue composition of the ore. The selective flotation of pyrochlore from carbonatite ore is not possible since calcite and dolomite have similar flotation properties as pyrochlore. In addition, in the presence of carbonates, the stable pH required for flotation of pyrochlore (i.e. 5.0-5.5) cannot be maintained. 

The calcite/dolomite in actual practice is recovered using fatty acid as a collector and starch or dextrin as the pyrochlore depressant during calcite-dolomite flotation. 

A number of studies have been conducted [1,2] in which different fatty acid modifications were examined. High selectivity and high calcite-dolomite recoveries were obtained with emulsified fatty acid with soda ash and sodium silicate. Table 22.2 shows the results from calcite/dolomite flotation using different fatty acid type collectors and various modifications. 

Calcite-dolomite collectors Recovery (%) Nb205 depressant used during CaO flotation % Nb205 in calcite concentrate Flotation pH... 

The effectiveness of emulsified fatty acid EMF2 was dependent on flotation pH. Figure 22.1 illustrates the effect of pH on calcite-dolomite recovery using 400 g/t collector EMF2. 

In actual plant practice, by removing the calcite-dolomite, the pyrochlore in the flotation feed is significantly upgraded. In some ores, which assay 0.4% Nb205 in the feed after calcite-dolomite preflotation, the pyrochlore assays in the pyrochlore flotation feed is over 1.2% Nb205. 

Van Kauwenberg3 has described the mineralogy and alteration of phosphate ores in Florida. Mineralogical composition varies by particle size. Francolite and then quartz are the most abundant minerals for plus 20-mesh particles (pebble), while the reverse is true for particles in the 20-200-mesh fraction (flotation feed). In the minus 200-mesh size fraction (clay waste) quartz, francolite, wavellite, crandallite, goethite, dolomite, and a variety... 

Naturally occurring talc is mined and pulverized before being subjected to flotation processes to remove various impurities such as asbestos (tremolite) carbon dolomite iron oxide and various other magnesium and carbonate minerals. Following this process, the talc is finely powdered, treated with dilute hydrochloric acid, washed with water, and then dried. The processing variables of agglomerated talc strongly influence its physical characteristics. " ... 

Floatabilities of francolite and dolomite using oleate as collector are shown in Figs. 4.28 and 4.29 as a function of oleate concentration and pH. It can be seen that the floatabilities of dolomite and francolite are quite similar with a sudden increase at an oleate concentration of 1.6 X 10 mol/1. Selective flotation of francolite from dolomite might be expected only above pH 9 or below pH 5. However, flotation of a binary mixture of dolomite and francolite (50 50) with 1.7 x 10 mol/1 oleate at pH 5.2 and 9.0 yielded poor separation. The loss of selectivity during flotation may be attributed to the interactions among the dissolved mineral species from minerals and oleate as well as the formation of oleate precipitates (Amankonah and Somasundaran, 1985). Depletion isotherms for labeled oleate on francolite and dolomite are shown in Fig. 4.30. Both francolite and dolomite show a two-region (II and III) linear isotherms with a break at a residual concentration of... 

Overall behavior of the dolomite/francolite-oleate flotation system is depicted schematically in Fig. 4.38 and its implications are discussed below ... 

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. 

These are used to prevent flotation of one material while floating another. Lime and NaCN are examples. Both of these depress pyrite. Dichromate is a depressant for galena. HF is used to depress quartz in the flotation of feldspar with amine collectors. Sodium silicate is also a quartz depressant. Quebracho depresses calcite and dolomite in the flotation of fluorite with fatty acids. 

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