Hematite separation processes

It will be both interesting and instructive to describe the separation process principles for two substances one a quartz-magnetite, and the other a quartz-hematite. The quartz-magnetite when ground would consist of liberated quartz particles, liberated magnetite... 

The most familiar of the C-frame, matrix-type industrial magnetic separators are the Carpco, Eriez, Readings, and Jones devices. The Carpco separator employs steel balls as a matrix, Eriez uses a combination of expanded met matrices, and the Readings and Jones separators have grooved-plate matrices. Capacities for this type of unit are reported to up to 180 t/h (in the case of Brazdian-hematite processing). 

Flotation is certainly the major separation method based on the surface chemistry of mineral particles. It is, however, not the only method. Selective flocculation and agglomeration may be mentioned as other methods used commercially to a limited extent. The former is for hematite, while the latter is for coal and finely divided metallic oxide minerals. Both processes use the same principles as described for flotation to obtain selectivity. In selective flocculation, polymeric flocculants are used. The flocculants selectively adsorb on the hematite, and the hematite floes form and settle readily. Thereby separation from the sili-... 

At the completion of the reaction, the aniline is separated from the iron oxides by steam distillation and the umeacted iron removed. The pigment is washed, filtered and dried, or calcined in rotary kilns to hematite (Plate 20.1, see p. XXXIX). Considerable control over pigment properties can be achieved in this process by varying the nature and concentration of the additives and the reaction rate the latter depends on pH, the rate of addition of iron and nitrobenzene and the type and particle size of the iron particles. Two advantages of this method are that a saleable byproduct, aniline, is produced and that there are no environmentally, harmful waste products. 

Suspensions of hematite have also been used and studied for other aims than photooxidation of water, e.g. catalytic oxidation of sulphur dioxide in aqueous solutions [52]. Aqueous dispersion of semiconductor particles could be an easy and attractive way to photooxidise water, but they have the drawback that dihydrogen and dioxygen are produced simultaneously in the same suspension. Apart from the separation problem the two produced gases may create a pathway for back reactions that reduces the yield of the overall photo-oxidation process. The latter obstacle can partly be avoided by addition of Na2C03, which was successfully shown by Arakawa et al [115]. 

Mineral Beneficiation Electrostatic methods are widely used in the processing of ores with mineral concentrates. Generally, electrostatic separation is used as a part of an overall flow sheet comprising various combinations of physical separation procedures. It is particularly well established in the processing of heavy-mineral beach sands from which are recovered ilmenite, rutile, zircon, monazite, silicates, and quartz. High-grade specular hematite concentrates have been recovered at rates of 1000 tons/h in Labrador. Applications also include processing tin ores to separate cassiterite from columbite and ilmenite. Refer to Fig. 19-61 . 

Iron is seldom found in the elemental form needed to make steel. Metallic iron must be separated and purified from iron ore—usually hematite, Fe203. This process takes place in a blast furnace in a series of redox reactions. The major reaction in which iron ore is reduced to iron metal uses carbon monoxide gas as a reducing agent. 

After the reduction of Fe(III) by zinc blend concentrate and after the separation of the solute noble metals, ferrous iron is oxidized to ferric iron which then precipitates in the form of hematite. The intermediate noble metal yields from the Jarosite and Hematite processes are compared in Figure 9.7. The quality of the hematite produced permits its utilization in the cement industry as a coloring material. For use in the steel industry, the zinc content of hematite must be reduced from 1% to 0.1%. 

Iron-zinc separation fix)m solutions has always presented a challenge to the hydrometallurgist, b industrial practice, iron and zinc are separated by selective precipitation of an iron (III) precipitate from zinc. Various processes are or have been practised commercially depending on the form of the final iron precipitate (jarosite, goethite, para-goethite and hematite). Apart fix)m the inherent difficulties of each of these processes, iron is lost in those systems it cannot be recycled and therefore becomes a consumable, and this is likely cost prohibitive in the process considered here. 

The structure and performance of starch had been discussed in the former Chapters. Based on the flotation application of starch, starch is mainly used to depress hematite in the reverse flotation process. In addition, starch depressants are also applied in the flotation separation of Cu-Mo ore [7, 8]. The modified products of starch can selectively depress quartz, silicate, and talcum. 

Iron behavior of pyrite cinder in roasting process at 600 was studied, which can be seen in Table VI. It showed that the iron grade of roasted cinder increased for decomposition and volatilization of part of sulfate and crystal water. A large number of hematite was reduced to magnetite which led to susceptibility dropping considerably, and made roasted cinder easy to be separated. 

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