CS257351B1 - A method of producing sintered magnesia from breuneritic magnesites - Google Patents

Abstract

The solution concerns the industry producing refractory materials from natural Breuneric magnesite. The aim of the solution is to increase the proportion of technologically usable magnesite for the production of sintered brick-quality products with a low content of calcium oxide and silicon dioxide. The essence of the solution lies in the magnetization roasting of grown magnesite or magnesite raw material concentrates obtained by gravity treatment at a temperature of 1,000 to 1,300 °C, sieving particles smaller than 6 mm from the calcinate, which are magnetically separated into concentrate and waste, crushing the fraction above 6 mm to a grain size below 6 mm and its magnetic separation and direct sintering of magnetic concentrates at a temperature of 1,550 to 1,800 °C to sintered magnesia.

Description

I 3 4 237351

The invention relates to a process for producing sintered magnesia from breuneritic magnesites.

According to the present processes, natural burneritic magnesia after felling is modified by gravity pathways in hydrocyclones (1 to 10 mm fraction) and heavy suspensions (10 to 60 mm fraction). The obtained urea concentrates are fired in shaft or rotary kilns at a temperature of 1500 ° C on sintered magnesium. The disadvantage of this process is the lack of high-quality product. As a result, a magnetic separation of the final saliva is required. A magnetic concentrate is obtained, which is used for the production of shaped constructions (in addition to TS). The uncoated portion (hereinafter OS) containing 4-20% calcium oxide used as magnesium to repair steel furnace exudates and its production in the main TS product is now far beyond demand. With this procedure, it only rates 20% of the production of TS produced and 20% of the production of OS. About 60% of the raw material to be treated is waste treatment, but still contains a significant amount of magnesite substance. Another method used in the treatment of natural magnesite is flotation, which allows the processing of grown magnesia on TS by utilizing 40% of the raw material recovered. The disadvantages are the high economic costs, environmental problems associated with waste water technology and the problem of storing the waste grain below 0.2 mm. From the patent literature, it is known to remove undesirable components from magnesite raw materials on the basis of the different hydration properties of magnesium oxide and calcium oxide described in AO 198 555 - Staroň "Method of producing salted magnesium". The disadvantage of this process is the technological complexity in the hydration node of the calcined feedstock. Another method of enrichment of magnesite and clinker production is described in AO 212 025 Mi- chalik - Kubran - Brodňanský "Production of sintered products from breunerite magnesites", the principle of which consists in combining gravity treatment and magnetic separation of calcined magnesite, with concentrates from the magnetic treatment is reduced to a high degree of dispersion, the briquettes are briquetted and the briquettes are sintered. The disadvantage of this process is the high investment and operating costs of the milling and briquetting technology line.

SUMMARY OF THE INVENTION The process of producing sintered magnesium from breuneritic magnesites according to the invention, which avoids the disadvantages described, consists in the fact that the magnesite raw material obtained by the magnesia or gravitational treatment is obtained at a temperature of 1000 to 1300. ° C, the sieve is separated from the calcite by particles smaller than 6 mm, which are magnetically separated into concentrate and waste, the grain above 6 mm is broken down to a grain size below 6 mm, which is magnetically divided into concentrate and waste and concentrates are directly sintered at 1550 to 1800 ° C for sintered magnesium. The advantages of the proposed solution over the existing practice of magnetic sintered products consist in higher selectivity of the calcining, higher utilization of the magnesite substance and higher quality of the product. The solution proposed does not require an investment-intensive line for flotation and processing of flotation concentrate to sinter (calcination, briquation, high-temperature firing) compared to the technology-based magnesite clinker. The advantage of the proposed solution in comparison with the solution described in AO 198 555 is its simplicity, when special hydration of calcium oxide is not required to obtain concentrate for the production of salted magnesia. Compared to the solution described in AO212 025, the fineness, briquetting and briquette firing of the calcinate magnetic concentrate is known to be replaced by its direct rotation in the rotary kilns, thereby significantly reducing the operating and investment costs of producing sintered magnesia while retaining quality qualities. clinker.

Described method for producing sintered magnesium from breuneritic magnesites, obtaining a sinter with a density of 3.4 grams. cm-3 and more than 60 wt. % of the TS for the production of TS may already be advantageously used in existing magnesite processing plants, while the technological changes would be minimal and consist in the preparation of transport routes and the use of a thermal aggregate for the purpose of calcination. Sintered magnesia is used for the production of high quality refractory shaped constructions of non-monolithic materials. Example 1

Natural magnesia, 0.2-60 mm in size, and-Calcium oxide 11.5%, 1.00% silicon dioxide, 6.80% iron oxide, and 80.7% magnesium oxide - reported per annealed condition, calcined in a rotary kiln, 1200 ° C to a density of 2.70g. cm-3 and spread to granular grades — 1, 1-3, 3-6, +6 mm. Grain grades — 6 mm were each magnetically divided into concentrates and wastes. The grain size class + 6 mm was sparingly under 6 millimeters and spread to fractions -1, 1-3.3 mm, which were each separately magnetized to concentrate and evaporate. Tab. 1 shows the concentrate yield and qualitatively indicators (set values after annealing) of the magnetic separation. The obtained concentrates were further high-temperature-burned in a rotary kiln at 1700 degrees Celsius to sintered magnesium with

Claims (2)

257351 5 6 with a weight of 3.40 g. cm 3 3 and 60% of the reduction was calculated for the production of TS - calcium oxide 2.72%, silicon oxide. % 0.35%, magnesium oxide 89.10 ° / s, while the magnetic treatment of calcinate Table 1 Proportion Yield (w / w) CaO content (w / w) S1O2 content (w / w) Concentrate 65.5 Waste 34 , 5 Submission 2.72 0.35 27.58 2.20 11.31 0.98 Example 2 A natural magnesite concentrate of 10-40 mm in size and a composition of calcium oxide 5.12p., Silica 0.89%, iron oxide 7.38%, magnesium oxide 86.64%, reported in the annealed state, calcined in at a temperature of 1200 ° C to a density of 2.70 g. cm-3 and further modified as in Example 1. Products with yields of quality according to Table 2 were obtained. The obtained concentrates were further burned in a 700 ° C rotary kiln for sintered magnesium with a weight of 3.40. g. cm-3 and the composition calcium oxide 1.77%, silica 0.56p., iron oxide 7.67% and magnesium oxide 90.0%. Magnetic treatment of calcinateTable 2 Proportion Yield (wt.%) CaO content (wt.%) S1O2 content (wt.% J Concentrate 64.7 1.77 0.56 Waste 36.3 11.26 1.41 Submission a, 12 0 , 86 SUBJECT A method of producing sintered magnesia from natural breunerite magnesite characterized in that magnesite-based raw material concentrates obtained by magnesia or gravitational treatment are obtained at a temperature of 1000 to 1300 ° C, and are separated from the calcine. sieve particles smaller than 6 LOAD millimeters, which are magnetically distributed by concentrate and waste, grain above 6 mm serrated to grain size below 6 mm, which is self-sizing to concentrate and waste concentrates are sintered at 1 550 to 1800 ° C on sintering.