Kaolin improvement

Fig. 2. (a) Brightness improvement obtained by the use of kaolin as a filler in paper and (b), opacity improvement obtained as pulp fibers are replaced with various kaolins. In both cases, A represents fine-particle calcined clay B, high brightness No. 1 kaolin C, coarse-particle water-washed kaolin and D,... 

Inks. Refined kaolin is a common ingredient in a large variety of printing inks (qv). In addition to extending the more expensive polymers present, ka olin also contributes to improved color strength, limits the penetration of the ink into the paper, controls rheology, and improves adhesion. Kaolin for this appHcation must usually be as white as possible and free from oversize particles. Surface treated clays are used to improve compatibiHty with oil-based ink. Clays can also be an ingredient in the newer water-based or uv-cured inks. 

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. 

The table data show that the stress/strain properties of compositions are improved by additional dispersion (mixing). Ultrasonic analysis is sufficiently reliable and informative as a means of mixing quality assessment. The very small change of the characteristics for filled compositions (chalk + kaolin) can be due to the fact that these fillers are readily distributed in the matrix as they are. 

Many inert pigments (often known as fillers) are incorporated into paper in addition to the cellulosic fibres. They may be added to improve certain optical properties—in particular opacity and brightness—or simply as a cheap replacement for costly fibre. The two most common pigments are kaolin (china clay) and chalk (limestone), but talc and speciality pigments such as titanium dioxide are also used. The particle size for general purpose fillers is normally expressed as an equivalent spherical diameter (esd) and this is determined from sedimentation data. Values for the common paper-... 

An evaluation of numerous clays, including kaolins and bentonites of comparable particle size and distribution, revealed a wide variation in the properties of LDEE-clay composites prepared under identical conditions with similar loadings. This may be attributed to the interference with the radical reactions involved in the coupling sequence. This is confirmed, in part, by the finding that the most effective clays were those which were reported to have been treated with sodium polyphosphate to improve their dispersibility in water during papermaking processes. Solomon reported (1) that treatment of the clays which inhibited radical reactions with sodium polyphosphate reduced the inhibition. 

Henry et al (23) have collected experimental data on cross-flow electro-filtration of Kaolin clay suspensions and oil-water emulsions. Since both the Kaolin particles and the oil droplets are negatively charged in aqueous suspensions, a direct electric field will always give higher filtration rates than cross-flow filtration alone. The level of improvement depends on the intensity of the fluid shear and the electric-field strength. Figures 47 and 48 present data for the Increase in flux with electric field strength for the oil-water emulsion and the clay suspension. 

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 ... 

Measures taken to minimise the amount of unadsorbed polymer in solution have been shown to improve the viscosity performance of both kaolin and calcium carbonate slurries. These include adjustment of the pH or initial neutralisation of the polymer to increase its affinity to the surface and fractionation of the polymer to reduce the width of its molecular weight distribution. 

To further prove the efficacy of S-8706 and its applicability on a full-scale, a plant trial was conducted at Thiele Kaolin Company s flotation plant. The average SE value obtained with AP 6493 before the trial run was 70. Replacing AP 6493 with S-8706, the flotation performance during the trial run improved to... 

J-F. Wilson, USP 3223185(1965) CA 64, 6153(1966) [The instability of AN (used in expls and fertilizers) in storage results from change in water content or changes in vol at the phase transition points. The improvement in stability is achieved by coating the AN particles with a compn consisting of a major amt of a clay (such as attapulgite, kaolin or diatomaceous earth), and a minor amt of an oil-sol alk-earth metal salt of petroleum sulfonic acids (sucb as Ca petroleum sulfonate)]... 

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