Chemicals of Commerce (Snell, F. D.; Snell, C. T.)

Abstract

This newcomer to the textbooks on colloid chemistry is one of the best reviews of the subject. It is addressed to graduate students or to advanced undergraduates in chemistry, as well as to students in allied sciences.The author rightfully states that, "The science of colloid chemistry bridges the gaps between the various physical and biological sciences. It has become an indispensable tool without which it is impossible to explain many scientific phenomena. It is the one field of chemistry which can claim to be the chemistry of everyday life."The book is refreshing in that it is not simply a rehash of some of the material in a few leading texts filled out by references to papers which happened to have been published in the last year or two.On the contrary, it is a fair cross-section through the material in this field, and the references are distributed over the most important papers throughout the whole development of the subject. The theoretical side is somewhat weak, but this in part reflects confusion among various schools, and it is fully compensated for by the wealth of interesting factual matter. Several chapters might be modernized. For example, the discussion of sedimentation hardly does justice to Svedberg's oil turbine ultracentrifuge or to the established theoretical treatment of Mason and Weaver, Lamm, Faxen, and Archibald.The book consists of four parts. The first comprises surface chemistry, including adsorption and catalysis. The second is devoted to the preparation and properties of lyophobic systems with separate chapters on aerosols, emulsions, and foams, dialysis and ultrafiltration. The third part deals with lyophilic systems, sols, gels, and jellies. Part IV gives much interesting information with regard to the biocolloids, with further chapters on foods, biocatalysts, colloid factors in growth and movement, and colloids in the blood and nervous system, concluding with one on colloidal medicines. At the end there is a five-page list of reference books.The book is beautifully illustrated, and the text is particularly clear. It should be widely read. The factual information will appeal to the imagination of many students and lead to their giving the subject much closer attention.

A review of the physicochemical properties and flotation of pyrrhotite superstructures (4C – Fe7S8/ 5C – Fe9S10) in Ni‐Cu sulphide mineral processing

“…After magnetite, monoclinic pyrrhotite (Fe 7 S 8 (4C)) has the highest magnetic susceptibility, large enough that it can easily be separated by low-intensity magnetic separators. [5,6] Generally, the 4C variety is the sole "magnetic/monoclinic" pyrrhotite, whereas the intermediate NC superstructures (5C, 11C, and 6C) are grouped together as "non-magnetic/hexagonal" pyrrhotite. Numerous magnetic studies have been conducted on natural and synthetic pyrrhotites, [24,38,[46][47][48][49][50][51][52][53] most often on the two common superstructures (4C and 5C).…”

“…to contain more Fe(III) surface sites than 5C non-magnetic pyrrhotite (Fe 9 S 10 ), Table 2, which would promote higher xanthate adsorption onto 4C. A comprehensive study by Kolahdoozan [9] was conducted on three samples (synthetic 4C and 5C and a natural ore containing 4C pyrrhotite) over a large pH range (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Potassium n-amyl xanthate (PAX) collector adsorption studies were conducted under various conditions (as is, oxidative, cyanide, and copper preconditioning) to infer differences in the superstructure-collector interactions at flotation-relevant pH (7, 8.5, and 10), displayed in Figure 15.…”

“…Merensky Reef, South Africa) are special cases where its recovery is sought. [5,6] In the following sections, pyrrhotite flotation is initially discussed under a general context with subsequent focus on superstructure flotation.…”

“…Useful references for the stated mechanisms and operational rejection strategies are Rao and Finch, [94] Bozkurt et al, [95] Kelebek, [98] Senior et al, [18] Khan and Kelebek, [99] Miller et al, [6] Lawson et al, [10] Manouchehri, [5] Lawson et al, [14] and Wills and Finch. [78] Aside from these strategies, depressants are added to further decrease pyrrhotite's flotation response, with three common depressants being diethylenetriamine (DETA), triethylenetetramine (TETA), and cyanide (CN -).…”

“…Pyrrhotite containing PGEs in solid solution, discrete fine-grained platinum-group minerals (PGM), Ni in solid solution, or very fine-grained disseminated pentlandite are among the few exceptions where its recovery is sought. [5,6] Historically in Canada, pyrrhotite was recovered to the base metal concentrate (e.g. nickel-copper sulphide) from mineral processing plants that fed smelting operations, resulting in significant SO 2 emissions and large slag volumes that limited nickel throughput, thereby increasing smelting costs.…”