Feldspar, flotation

The fine mica fraction is deslimed over 0.875—0.147-mm (80—100-mesh) Trommel screens or hydrocylcones, or is separated with hydrosi2ers. The deslimed pulp (<0.589 mm (—28 mesh)) of mica, feldspar, and quart2 is then fed to a froth flotation circuit where these materials are separated from each other either by floating in an acid circuit with rosin amine and sulfuric acid (2.5—4.0 pH), or an alkaline circuit (7.5—9.0 pH) with tall oil amine, goulac, rosin amine acetate, and caustic soda (see Eig. 2). 

Sulfide collectors ia geaeral show Htfle affinity for nonsulfide minerals, thus separation of one sulfide from another becomes the main issue. The nonsulfide collectors are in general less selective and this is accentuated by the large similarities in surface properties between the various nonsulfide minerals (42). Some examples of sulfide flotation are copper sulfides flotation from siUceous gangue sequential flotation of sulfides of copper, lead, and zinc from complex and massive sulfide ores and flotation recovery of extremely small (a few ppm) amounts of precious metals. Examples of nonsulfide flotation include separation of sylvite, KCl, from haUte, NaCl, which are two soluble minerals having similar properties selective flocculation—flotation separation of iron oxides from siUca separation of feldspar from siUca, siUcates, and oxides phosphate rock separation from siUca and carbonates and coal flotation. 

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. 

The electrostatic separation method is the exclusive choice in some specific situations, for example in the cases of rutile and ilmenite deposits. These deposits generally contain minerals of similar specific gravities and similar surface properties so that processes such as flotation are unsuitable for concentration. The major application of electrostatic separation is in the processing of beach sands and alluvial deposits containing titanium minerals. Almost all the beach sand plants in the world use electrostatic separation to separate rutile and ilmenite from zircon and monazite. In this context the flowsheet given later (see Figure 2.35 A) may be referred to. Electrostatic separation is also used with regard to a number of other minerals. Some reported commercial separations include those of cassiterite from scheelite, wolframite from quartz, cassiterite from columbite, feldspar from quartz and mica, and diamond from heavy associated minerals. Electrostatic separation is also used in industrial waste recovery. 

Cationic flotation of tantalite columbite has also been studied on several ore types that contain tourmaline, feldspar and muscovite as the major gangue minerals [3], The effect of aliphatic mono-amine on flotation of Ta/Nb is presented in Figure 23.3. 

The cationic flotation of Ta/Nb was not effective, as they tend to float feldspar-bearing minerals. The effect of some amines on Ta/Nb-Zr bulk flotation is illustrated in Table 23.6. 

The ore used in this example contained a mixture of pyrochlore and columbite as the major niobium minerals. The tantalum is mainly associated with columbite. The major gangue minerals present in this ore were soda and potassium feldspars with small amounts of mica and quartz. Beneficiation of this ore using cationic flotation, normally employed for flotation of niobium, was not applicable for this particular ore, since most of the mica and feldspar floated with the niobium and tantalum. The effect of amine on Ta/Nb flotation is illustrated in Figure 23.9. The selectivity between Ta/Nb and gangue minerals using a cationic collector was very poor. 

Minerals as found in nature are always mixed together (e.g., zinc sulfide and feldspar minerals). In order to separate zinc sulfide, the mixture is suspended in water, and air bubbles are made to achieve separation. This process is called flotation, where an ore heavier than water is floated by bubbles. 

Although flotation was developed as a separation process for mineral processing and applies lo the sulfides of copper, lead, zinc, iron-molybdenum, cobalt, nickel, and arsenic and to nonsullides, such as phosphates, sodium chloride, potassium chloride, iron oxides, limestone, feldspar, fluorite, chromite, tungstates, silica, coal, and rhodochrosilc, flotation also applies to nonmineral separations. Flotation is used in the water disposal field, particularly in connection with petroleum waste water cleanup. 

Alkali feldspars do not occur in pure form in nature. The deposits are permeated by accessory minerals. Modern beneficiation methods (flotation, magnetic separation),... 

A. P. Pikkat-Ordynskaya, Flotation separation of monomineral fractions of galena, pyrite, chalcopyrite. Sphalerite, quartz and feldspar, Aktsessornye Miner. Izrerzhennykh Porod. 75-77 (Russ) (1968). 

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. 

Henuitite Quartz Fatty acids, amines sodium silicate Starch, dextrin attd feldspar, rii% second stage feldspar is floated by depressing quartz with HF Flotation of hematite using hit ... 

The flotation performance of this modified diamine is better than that of monoamine in the separation of scheelite from calcite. The selectivity of diamine is better than that of monoamine in the separation of feldspar from quartz. 

It had been discovered very early that macromolecule compounds can be used as flotation collector. For example, gelatin is the collector of quartz. Casein can be used as the collector of feldspar and quartz. The main ingredients of gelatin and casein are proteins and amino acids. The flotation results of feldspar and quartz using amino acid are shown in Fig. 2.4. 

---