At the Magnesite Combine a department for the dressing of Satkinsk ares in heavy suspensions is currentiy in operation [i].The production schedule of this department includes sieving the original ores Ln~o fractions of !50-60, 60-78, and 8-0 mm; the first two fractions are dressed in heavy suspensions in drum and conical separators. ~he 8-0 mm sieve fraction, of which the original ore produces 20-25%, has a concentration of 1.8-5.2%* of CaO and 1.0-3.5% of SiO 2 and is not dressed; it cannot, in general, be used in the production of refractories in accordance with the production instructions currently valid at the Magnesite Combine. The development of an effective system of dressing this sieve fraction would make it possible to bring into production some additional magnesites which at present are stored in dumps.~lhe Sibelectrostal' Plant has developed a gravitation-flotation method for dressing this sieve fraction; this includes the wet screening into 8-0.6 and 0.6-0 mm fractions, the separation of the 8-0.6 mm fraction in a low-pressure hydrocyclone in a heavy suspension [2], and foam separation of the 0.5-0 mm fraction ( Fig. 1).Tae gravitation part of the process was checked in semiindustrial conditions using a sample of 370 tons with a 44.47% concentration of MgO, 3.3% of CaO, and 1.55% of SiO 2. During the tests the experimental dressing shop worked at a productivityof 4 tons/h in relation to the original feed. ~he 8-0.6 mm fraction was dressed in a suspension of density 2250 kg/m 3 in a low-pressure hydrocyclone, diameter 250 ram, mounted at an angle of 27 ~ to the horizontal. The input pressure was 49.03 kPa, the diameter of the sand nozzles 30 mm, and of the discharge nozzle, 60:ram. As the heavy agent we used ferrosilicium of grade Si-15 plus 5% of a magnetic concentrate to ensure the stability of the suspension. 2he suspension was regenerated by drainage and by washing out the heavy agent in self-balancing screens and by magnetic separation in a weak field.As a result of the dressing to give the gravel of the hydrocyclone, a Grade [II concentrate was separated; this amounted to 61.1%, with concentrations of CaO of 1.75% and of SiO 2 of 0.9%; the waste railings containing 13.3% CaO and 3.9% SiO2 were discharged.The additional processing of the 0.6-0 mm fraction was carried out by foam separation under laboratory conditions. From the original product, which contained 2.5% CaO and 2.04% SiO2, as a result of removal of 20 #m slurry (i.e., grains finer than 20 pm were removed) by means of the main separation and four repurifications, 11.1~ of Grade I concentrate was obtained; this contained 0.8% CaO and 0.37% SiO 2. Grade III concentrate (9.6%) was also obtained with a concentration of 1.86% CaO and 1.15% SiO 2. 2he yield of tailings (total with slurry) was 6.6% with a concentration of 6.3% of CaO and 6.2% of SiO 2.As a result of the dressing of the 8-0 mm sieve fraction, Grades I and III concentrates were obtained in amounts of 11.1 and 70.7% with a concentration of 0.8 and 1.77% CaO and 0.37 and 0.93% SiO...
In 1980 the electric power transmission lines were constructed; work is in progress on preliminary drainage of the overburden and on capital works. BENEFICIATION OF ~GNESITE ORES BY FROTH SEPARATION V. E. Potapenko~ D. I. Suvorova, and V. V. Tyuryukhanova UDC 622.765.4:622.368.2 The Uralmekhanobr institute and the Sibglektrostal ~ Works have developed and tested in the laboratory and pilot-plants various schemes for beneficiation of magnesites of the Satkin, Talsk, Savin, Semibratskii, and other deposits [1-4].The best magnesite concentrates were obtained by a flotation scheme providing for crushing of the ore to the -0.2 mm fraction, removal of the slime with grains smaller than 20 ~m, and flotation of the sands in a soda medium with an aliphatic acid collector using sodium hexametaphosphate as depressant.The magnesite losses with the slimes are about 20%.
The Siberian Electric-Steel Factory together with the Magnezit Combine is researching into the possibility of improving the quality of magnesite powders obtained by dry magnetic separation. It is known that when the magnesite powders contain free calcium oxide, the quality of the refractories is greatly impaired. Aging magnesite powder with the aim of sl~king the lime complicates the technology and does not completely eliminate its harmful influence [1].Earlier experiments to reduce the calcium oxide content by dry magnetic separation [1, 2] showed that into the magnetic product are extracted the relatively purer grains of powder with respect to the concentration of calcium oxide. The beneficiation schemes were not recommended. The present laboratory studies with the dry magnetic separation (DMS) were made with two samples (Nos. 1 and 2) obtained by burning the raw material in rotary kilns at the Magnezit Combine. Sample No. 1 consisted of fired raw mineral (magnesite grade III), and sample No. 2 --fired powder fractions --8 mm (screenings) from magnesite obtained at the combine when sieving raw mineral being sent for beneficiation on heavy suspensions. The screening of samples Nos. 1 and 2 with subsequent analysis of each fraction showed that they consisted of material with a grain size of --25 and --8 mm, respectively, and furthermore the calcium oMde in both samples was distributed uniformly and concentrated in the main in the coarse fractions (> 2 mm). In mineral composition~ the samples consisted of 79.5-80.5% periclase, and the impurities consisted of lime (6-7%7, silicates (7.5-9.5%), magnesioferrite, magnesite (3%), and other minerals (2%).The main difference between No. 1 and No. 2 was the finer dissemination of the lime in No. 2 (predominant sizes of the lime 0.002-0.08 mm against 0.02-0.5 mm in No. 1). The grain sizes of the remaining impurities in both samples were 0.01-0.004 mm, and all the minerals were closely associated with the periclase. The dimensions of the lime disseminations in the coarse fractions were greater than in the fine fractions.Starting from the unequal distribution of calcium oxide over the fractions, DMS was made on the classified material, choosing the optimum schedule for each fraction. Experiments with DMS were made on the induction-roller separator 138B-SE (upper limit of coarseness for the material being enriched 2 ram).The results of DMS for sample 1 showed that DMS more effectively reduces the content of CaO in the coarse fractions: the quantity of fines (< 2 ram) after DMS is improved slightly. In order to separate the magnetic product from the coarse fractions the strength of the magnetic field should be 960 kA/m. With a reduction in the coarseness of the original feed, the magnitude of the optimum magnetic field strength is reduced (to 640 kA/m)o On the basis of the overall factors for beneficiating, the fractions + 2 and --2 mm we conclude that it is beneficial to enrich the fractions --2 mm for sample No. 1.Silicon dioxide during the separation of the coarse fraction...
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