Sorting and screening

MgO, and sulfur and phosphorus content. In some operations high-grade ore is selectively mined, hand sorted and screened, and sold as lump and fines. More commonly the high-grade lump material is removed by hand, and the reminder is crushed and ground before beneficiation. LIBS may be used for chromite sorting and Mg, Al, Si contents evaluation (Fig. 8.12). 

Sorting and screening. Input-output analysis can be used to order markets and industries according to a number of criteria (e.g., size, category, energy intensiveness, etc.). For example. Table 4.10 screens all industries to determine which are the largest suppliers of the CPI. 

Directed evolution of enzymes has been used to improve the reducing function of the enzymes. For example, this method was used to eliminate the cofactor requirement of B. stearothermophillus lactate dehydrogenase, which is activated in the presence of fructose 1,6-bisphosphate [12]. The activator is expensive and representative of the sort of cofactor complications that are undesirable in industrial processes. Three rounds of random mutagenesis and screening produced a mutant that is almost fully... 

What can be done if there is not an exact literature precedent for the required enzymatic transformation In these cases some sort of screening procedure may be necessary, either by direct screening of commercial enzymes, culture collections and environmental isolates, or by using a bioinformatics-based approach to identify potential enzymes based on sequence information. 

Walker, J.D., Waller, C.W., and Kane, S., The endocrine disruption priority setting database (EDPSD) a tool to rapidly sort and prioritize chemicals for endocrine disruption screening and testing, in Handbook on Quantitative Structure Activity Relationships (QSARs) for Predicting Chemical Endocrine Disruption Potentials, Walker, J.D., Ed., SETAC Press, Pensacola, FL, 2003 (in press). 

Hydrophobic vinyl polymers such as chlorinated PVC films or polyvinyl-butyral may be used as a removable layer other materials used for this purpose are cellulose esters with added antistatic agents [231]. Such layers act as a unique sort of screen or shield for the main coating. Atmospheric dust adheres to this layer and is then removed along with the layer. 

Preparation of commercial baryte begins with sorting of the coarse mineral according to colour. This is then crushed and wet-ground to the required fineness, followed by levigation either by water or air-jet. Traces of iron discoloration may be removed by treatment with hydrochloric or sulfuric acids, followed by washing. The product is then dried and screened into a series of size grades. Feller also notes that traces of synthetic ultramarine (q.v.) may be added by the manufacturer to improve whiteness. 

However, even Cl expansion truncated to CI-SD may be too long and procedures were therefore looked for that could eliminate the least important CSFs. Shavitt distinguishes two stages in this selection, viz. preselection and screening of CSFs. The commonly used sort of preselection is to freeze... 

In the early lithium operations prior to 1960 a 610 m adit was used to enter underground workings in the lepidolite deposit at the 61 m level. Cars were loaded through overhead chutes, and then hauled by diesel locomotives to the beneficiation plant 450 m from the adit. The ore was crushed to about a — 76 mm size and screened, the waste removed by hand sorting from a conveyor belt, and the waste and fines stockpiled for potential future use. The concentrates were often of almost mineral collector s appearance, and they were trucked to the port at Beira for overseas shipment, and later delivered by the Rhodesian Railways. Petalite was mined in an open pit, and also hand sorted, but amblygonite was only obtained by selective hand mining in outcrop areas (Kesler, 1960). 

---