Suspensions mineral processing

Other than a nutritional role linked to mineralization processes, humic compounds have been hypothesized to directly affect plant nutrition, since it has been suggested that roots may take up low-molecular-weight humic molecules (21). Interestingly, plants have been ob.served to express carriers for amino acids (22) and small peptides (23) at the root level. Certain components of the humic fraction have been found inside root cells and were, moreover, translocated to the shoots (24,25). Recent experiments performed on rice cells in suspension culture seem to suggest that they may use carbon skeletons from humic molecules to synthesize proteins and DNA (26). 

From the process scheme of a C02-mineralization process (Figure P.15.7), in the meantime outdated, it appears that C02 needs to be compressed first, the feedstock needs to be ground to powder and mixed with water to a suspension and the reactor vessel produces a wet product and steam, that can be used to further dry the product. Keeping in mind that the process is meant to capture C02, what are some obvious questions to be raised ... 

J. Phys. Chem., 1962, 66, 1835 see also Audsley, A., Mineral Processing Information Note No. 5 "Flocculation of Suspensions of Solids with Organic Polymers ---- A Literature Sur-... 

Many of the applications of colloid and interface science to the mining and mineral processing industry can be found in the hydrotransport, flotation, and tailings processes. Although suspensions feature prominently in each of these, a range of emulsions, foams and suspensions can be found in this industry. Some examples are given in Table 10.1. 

Table 10.1 Some emulsions, foams, and suspensions in mineral processing. ...

Pachuca Tanks Air-agitated Pachuca tanks were widely used in mineral processing until the 1960s when the industry concluded that mechanical agitation was more economical and more effective for solids suspension. A description of Pachuca tanks can be found in previous editions of Perry s Handbook. 

Johnson, S.B. et al.. Surface chemistry-rheology relationships in concentrated mineral suspensions, Int. J. Miner. Process., 58, 267, 2000. 

A detailed descr tion is also presented on the reverse operation of flotation. Some solid materials may be present in the feed suspension vsbich are less dense than the surrounding fluid. Thus waste water is often contaminated with quantities of oil and grease. These substances will have a natural tendency to float on the sur ce of the feed water. Advantage may be taken of this eflEect by providing scrapers to remove the floating phase. The flotation process may be accelerated by the introduction of air bubbles into the feed attadunent of air bubbles to the contaminants will cause die latter to rise more quickly, hi mineral processes, solids which would normally tink in water can be caused to float by bubble attachment, after chemical modiflcation of the soUd sur ces. 

Flotation. The use of ak or gas bubbles to separate mineral particles by preferential attachment and subsequent flotation has been a feature of the mineral processing industry for many decades, but the application of the principle to solid-liquid separations is of more recent origin. The techniques have similarities but differences. In mineral flotation it is more common to use chemicals to enhance the collection of the particles and the stability of the ffoth and to produce the bubbles by beating air into the suspension, but in solid liquid separation it is more usual to dissolve air into the liquid under pressure, allowing the gas to expand out of solution under the lower pressure of the separation chamber, producing bubbles for the preflocculated particles to collect on without the need for further chemical addition. 

Medemblik, L. 1991. "Treatment of Qay Suspensions in MDPS s Potassium Chloride Flotation Plant, IN Preprints of the XVII Internationa/ Mineral Processing Congress, pp. 104-120, Dresden, Germany. 

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