Collectors for Nonsulfide Minerals

The functional group ia collectors for nonsulfide minerals is characterized by the presence of either a N (amines) or an O (carboxyUc acids, sulfonates, etc) as the donor atoms. In addition to these, straight hydrocarbons, such as fuel oil, diesel, kerosene, etc, are also used extensively either as auxiUary or secondary collectors, or as primary collectors for coal and molybdenite flotation. The chain length of the hydrocarbon group is generally short (2—8 C) for the sulfide collectors, and long (10—20 C) for nonsulfide collectors, because sulfides are generally more hydrophobic than most nonsulfide minerals (10). 

Collectors for nonsulfide minerals with an oxygen as bonding atom and with long enough hydrocarbon chain length can form less soluble compounds with all three kinds of metallic ions, except K and Na ions. In this case the values of solubility products for various ions are only slightly different from those of each other. 

Collectors for nonsulfide minerals containing O atom, such as fatty acids and sulfonates, react with various metallic ions by ionic bond, and they have high solubility in water. The solubility becomes low only when the hydrocarbon chains in the molecules are long. In contrast, collectors for sulfide minerals, such as xanthates possessing only a short chain, the S bonding atom reacts with metallic ions to form covalent bonds with lower polarity. 

The basic flow sheet for the flotation-concentration of nonsulfide minerals is essentially the same as that for treating sulfides but the family of reagents used is different. The reagents utilized for nonsulfide mineral concentrations by flotation are usually fatty acids or their salts (RCOOH, RCOOM), sulfonates (RSO M), sulfates (RSO M), where M is usually Na or K, and R represents a linear, branched, or cycHc hydrocarbon chain and amines [R2N(R)3]A where R and R are hydrocarbon chains and A is an anion such as Cl or Br . Collectors for most nonsulfides can be selected on the basis of their isoelectric points. Thus at pH > pH p cationic surfactants are suitable collectors whereas at lower pH values anion-type collectors are selected as illustrated in Figure 10 (28). Figure 13 shows an iron ore flotation flow sheet as a representative of high volume oxide flotation practice. 

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. 

In other words, solubility products of short chain collectors for sulfides are determined mainly by the bonding character that reflects the properties of the metallic ions. With collectors of nonsulfide minerals, the lower solubility product is the result of additive effects of long chain . In this case the bonding character is not closely related to the properties of metallic ions. Thus selectivity of collectors with S bonding atom is better than that of collectors with O bonding atom. 

The amount of collector used is necessarily very small because surface coverages of a monomolecular layer or less are required to impart sufficient hydrophobicity to the mineral. The usages typically range from 1—100 g of collector per ton of ore treated for sulfide flotation (typically 0.2—10% value metal content ia the ore) and 100—1000 g/1 for nonsulfide flotation (1—20% value mineral content) (10). 

Nonsolvent bath, polymer precipitation by immersion in, 15 808-811 Nonspecific elution, in affinity chromatography, 6 398, 399 Nonstationary Poisson process, in reliability modeling, 26 989 Non-steady-state conduction, 9 105 Nonsteroidal antiinflamatory agents/drugs (NSAIDs) 21 231 for Alzheimer s disease, 2 820 for cancer prevention, 2 826 Nonsulfide collectors, 16 649 Nonsulfide flotation, 16 649-650 Nonsulfide mineral flotation collectors used in, 16 648-649t modifiers used in, 16 650, 651t Nonsulfide ores, 16 598, 624... 

Understanding the adsorption of long-chain alkyl amines and their surface structure is significant for improved nonsulfide flotation technology and the development of new flotation chemistry for the flotation of nonsulfide minerals. In the middle of the twentieth century, Gaudin and Fuerstenau first studied the use of long-chain alkyl amines for the flotation of oxide minerals, particularly the flotation of quartz with primary dodecylamine (DDA) (Gaudin and Fuerstenau 1955). Their studies showed that the collector adsorption density and zeta potential at the solid-water interface are... 

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