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A flotation process is presented and the work carried out to find optimum conditions to minimise the colouring material in ground calcium carbonate is described. The feed material is the overflow product from a hydrocyclone, which results from using a Denver attritioning machine with semiautogenous grinding for 1 h at 1:1 ore/water ratio. By using sodium silicate as deprassant and oleic acid as collector with pH 9, the iron content (as colouring material impurities) is decreased from ,0 . 9 in the original sample to ,0 . 45 in the rougher concentrate. However, by cleaning the rougher concentrate, the iron content is decreased to 0 . 26%.

A jiowsheet combined high intensiry maglletic separation and jiotation was suggested for the preparation of supergrade concentrates suitable for the /)roduction of spollge iron. Fine grinding of El-Gedida iron ore assaying 50.55% Fe and 11.85% acid insolubles to-100 mesh was found to be imperative to reach a maximum degree of liberatioll. After desliming to remove the-15 P. siz e fraction , the dry " D ings" crossbelts magnetic separataor was employed for ore benefication at different rates of feeding, belt speeds and magnetic field intensities. Although the machine capaciry increases with the increase of feed layering , yet this will be made at the expense of the concentrate grade and the power consumption of the process. A satisfactory high grade rougher concentrate was obtained at about lJ.5 kG and one particle-layer feed. Multi/)le cleaning operations were investigated under different feeding conditions, whereb..v a standard grade concentrate assaying 57.84% Fe and 2.84~0 acid insolubles was obtained via one stell process only in the case of single particle-layer feeding. The fea sibiliry of reverse cationic jiotation for the overcleaning of such magnetic concentrate was studied by the application of the selective collector AroSUlf lvlG 98 A3. Preliminary caustic soda scru bbing of the concentrate (1.8 kg/t) at a solid/liquid ratio of 1 : 3 was recommended. Soluble starch (0.02 kg/t) , a specific depressant for iron oxide minerals, was employed in the presence of CaCl, (0. 1 kg/t). At /)H 11, solid/liquid ratio of 1 : 8 and amine/starch ratio of 10 : 1, the jiotation selectiviry is at the optimum. A final su/)erconcentrate assaying 60.7~o Fc (i .e. 66.77 "o Fc in the fired product), 1 .42~0 acid insolubles was obtained by a single ste/) cleaning operation at the optimum conditions with an iron recovelY of about 94 0 0 , Complete chemical anaiysis of this concelltrate confirmed its suitabiliry for the production of s/)onge iron. The /)roposed fiowsheet /)1"Qved to be more feas ible than the magnetic roasting-jiotation technique for the /Jreparatioll q[ such. superconcentrates .

In electroplating of ternary Zn-Ni-Fe alloy from the acidic chloride baths, the influence of iron codeposition on corrosion resistance and surface topography of the electrodeposits were investigated in comparison with Zn-Ni alloy deposits. It was found that the ternary Zn-Ni-Fe alloy showed better corrosion resistance in comparison with binary Zn-Ni alloy, even though both Zn-Ni-Fe and Zn-Ni deposits contained approximately the same nickel content. The best corrosion resistance, in 3% neutral sodium chloride solution, observed from the deposit having 16.74% nickel and 3.95% iron. The surface topography of the deposits was characterized by using scanning electron microscopy (SEM) in order to give more information about corrosion behaviors. It was found that the deposits with iron had finer grain size and more homogenous structure in contrast to that of Zn-Ni deposits.