Kaolin extraction

Inequality Re > H corresponds to the other case, when only a part of a penetrant is extracted by a developer and can form crack s indication. Such a situation can take place when one use kaolin powder as the developer. We measured experimentally the values Rj for some kaolin powders. For the developer s layer of kaolin powder, applied on tested surface. Re = 8 - 20 pm depending on powder s quality. 

In the pulp and paper industry, anionic and cationic acrylamide polymers are used as chemical additives or processing aids. The positive effect is achieved due to a fuller retention of the filler (basically kaoline) in the paper pulp, so that the structure of the paper sheet surface layer improves. Copolymers of acrylamide with vi-nylamine not only attach better qualities to the surface layer of.paper, they also add to the tensile properties of paper in the wet state. Paper reinforcement with anionic polymers is due to the formation of complexes between the polymer additive and ions of Cr and Cu incorporated in the paper pulp. The direct effect of acrylamide polymers on strength increases and improved surface properties of paper sheets is accompanied by a fuller extraction of metallic ions (iron and cobalt, in addition to those mentioned above), which improves effluent water quality. 

Reynolds Metal A process for extracting aluminum from clay by leaching with nitric acid. An essential feature is the pelletizing of the clay by calcination with kaolin in order to pro-... 

Sodium dithionite (Na2S204) is a reductant that is commonly used for the extraction of Fe oxides from kaolin and from soils (both to determine the total amount of Fe oxides and to improve the dispersibility of the day minerals Mehra Jackson, 1960). The overall reaction may be written as ... 

As Rosales and co-workers noted [48 ], vast amounts of chemical dyes (around 10 tons) are made annually worldwide [ 49]. Dye-containing effluents can make their way into runoff and wastewater, eventually settling in the soil. As these workers noted [48], with textile industries, as much as 50% of the dyes can be lost and disposed in effluents [50]. These dyes can have adverse effects on the environment and ecosystems they pollute. Previous extraction methods have had limited success in removal from soil, and a recent approach involved the use of Fenton s reagent with electrochemistry [48] testing removal of Lissamine Green (Figure 9) from a pseudo-soil matrix (kaolin). 

Ash. In ordinary wines the weights Of ash and extract are approximately in the ratio x xo. A greater proportion Of ash may be due to some treatment of the -wine, such as plastering, addition of alkaline salts to correct acidity, salt, phosphate, alum, or impure mineral substances (kaolin, Spanish clay) used as clarifying agents. 

Aluminum is the second most abundant metal on earth s crust. It is a common metal in tropical soils called laterites (red soils). It is extracted from bauxite that is a rich laterite by Bayer process that involves dissolution and separation of the oxide in caustic soda solution between 150 and 250°C and 20 atm of pressure. Though abundant and inexpensive, alumina based CBPCs are difficult to form because even in an acid solution the solubility of alumina is very low. This solubility, however, can be enhanced by a mUd thermal treatment and suitable CBPCs can be formed. Alumina is available commercially as calcined alumina called corundum, or as its hydrated forms such as aluminum hydroxide (Al(OH)3), as bohmite, (A1203-3H20), gibbsite (AI2O3 H2O) or in impure forms as in kaolin clay. These mineral forms and their use in ceramic formation are discussed in Chapter 11. 

Overpressure also has favourable effects in terms of the time needed to fill the extraction cell with solvent, especially for samples with small particle sizes [21]. However, the increased pressure can induce changes in the matrix surface resulting in a reduced extraction efficiency of analytes in some types of matrices [22-24]. Such is the case with the extraction of 4-nonylphenol from kaolin, which was quantitative at 100 atm at 100°C after 10 min of dynamie extraction, but required 30 min at the same temperature and 150 atm [25]. A similar effect was observed in the extraction of linear alkylbenzene-sulphonates from kaolin as can be seen from Fig. 6.2, the time needed for quantitative... 

Fig. 6.2. Effect of pressure on the recovery of spiked linear alkylbenzenesulphonates, extracted from kaolin samples at a temperature of 100°C. ( ) 100 atm, ( ) 50 atm, (A) 150 atm. (Reproduced with permission of Elsevier.)...

Dirt, soils, and clays Retention of particulates and colloids in turbid water supplies concn of fines in kaolin processing Polysaccharides and oligosaccharides Concn of starch effluents concn of pectin extracts... 

Raw kaolin is mainly extracted by open cast mining. Secondary deposits can be exploited using excavators, whereas primary deposits of kaolin are often washed out of the rock with a high pressure water jet. 

The extraction techniques in current use in most laboratories throughout the world are still based on the kaolin-acetone procedures of Albert (A2) and Loraine and Brown (L8) or the tannic acid method of Johnsen (Jl). There is little information in the literature regarding the reliability criteria of these methods. Loraine and Brown tested the accuracy of their kaolin-acetone method in a series of recovery experiments in which a reference material prepared from urine, HMG-20A, was added to urine and recovered the end point of the bioassay was the mouse uterus test for total gonadotropic activity. The mean percentage recovery was 76,... 

McArthur et al. (Ml) and others have demonstrated that extracts prepared by the tannic acid procedure are less toxic to experimental animals than those obtained by most other techniques including the variants of the kaolin-acetone method. Herbst et al. studied the accuracy of the tannic acid method by conducting recovery experiments involving the addition of the second International Reference Preparation for human menopausal gonadotropin (second IRP-HMG) to pools of normal male urine. They found that approximately 100% of the LH activity, but only 50% of the FSH activity, was recovered (H5). 

Recovery experiments such as those performed by Loraine and Brown (L8) and by Herbst et al. (H5) for the kaolin-acetone and tannic acid methods, respectively, are open to the criticism that the material used had itself been extracted from urine. It is possible that more reliable information with respect to the accuracy of those techniques would have been obtained if material extracted from pituitary tissue had been used. However, at the time of writing, experiments of this latter type do not appear to have been conducted. 

Absorbents, such as kaolin (a hydrated aluminum silicate clay mineral), pectin (a complex carbohydrate often extracted from fruits), and atta-pulgite (a hydrated magnesium aluminum silicate clay mineral), form a thickening powder that absorbs excess fluid and any bacterial toxins present (action of kaolin and attapulgite) and increases the consistency of the stool by forming a viscous colloidal solution (action of pectin). However, these agents may also absorb essential body enzymes and nutrients. 

A similar trend was observed when kaolin was leached for 1 hr. at 250°C with sodium carbonate solutions of different concentrations (Table IV). At the lowest concentration (0.2 M), part of the kaolinite was converted to the sodalite-type natrodavyne while the impurities were untouched. At the highest concentration of sodium carbonate (2.0 M), the kaolinite was converted to the cancrinite-type natrodavyne, and although the quartz was extracted, the illite remained. 

When kaolin was leached with 1.0 M sodium hydroxide at 250°C for 1 hr., most of the kaolinite appeared to be converted to analcime (Table IV). Increasing the concentration to 2.0 M resulted in converting most of the kaolinite to hydroxycancrinite (HC). In either case the quartz impurity was extracted but the illite impurity remained. Leaching kaolin with 2.0 M sodium bicarbonate at 250°C for 1 hr. converted the kaolinite to the sodalite-type natrodavyne, but it had no apparent effect on the impurities. 

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