SU718373A1 - Method of preparing magnesium oxide - Google Patents

Description

The invention relates to methods for producing magnesium oxide with a low content of calcium impurities.

A known method for producing magnesium oxide by reacting a magnesium-containing solution with sodium carbonate solution is set equivalent to the magnesium content when the initial solutions are introduced into a freshly precipitated suspension of trihydrocarbonate mesgni (TGCM), followed by separation of the precipitate of magnesium carbonate, it and thermal decomposition I.

The closest. / Is a method of producing magnesium oxide, which consists in treating magnesium- and calcium-containing brines with soda at 26-28 ° C, pH 8-8.5 and time 25 minutes. The precipitate is separated, washed and dried AND

The disadvantage of these methods is that when the brine is contacted with soda, a product with a Q ratio is formed. 100, i.e. same

 qO

as in the original brine.

The purpose of the invention is to reduce soda {calcium compounds in the product.

This goal is achieved by the method of obtaining magnesium oxide from brine containing magnesium and calcium salts by contacting the brine with soda, taken in an amount of 8–85% relative to magnesium in brine. with the subsequent separation of the precipitate from the mother liquor, its washing and calcination, and the process to the stage of washing the precipitate is carried out for 30 -60 minutes

The introduction of soda in the amount of 8O-85% relative to magnesium in brine with the duration of contact of the precipitate with the mother liquor of 30-6O minutes allows

zit ratio in the product compared to the original solution by 3-5 times when using brine with the ratio

. , p-1.0% and 1.5-2 times.

when using brines with the ratio j. , S-3, O%. With the addition of the amount of soda injected above 8S%, the CaO content in the product increases, approaching the rj in the initial brine with an equivalent ratio of initial reagents. Reducing the amount of soda injected. below 80% does not increase the efficiency of purification of the product from calcium compounds. An increase in the contact time of the precipitate with the mother solution with a solution above 60 min at 718373 leads to an increase in the calcium content in the product by reducing the supersaturation of the mother liquor with calcium carbonate. With a reaction time of less than 30 minutes, the precipitated TGCM has a fine cristachic structure, which increases the moisture content of the filtered paste. The results of the experiments at various ratios between soda and magnesium brine are represented in the table.

Example. A 2.5 liter continuous reactor with a capacity of 2.5 l is fed to a Sivash plant containing%, 2 and Ca 0.2 9 soda solution with concentration.

The feed rate of brine is 3.14 l / h, and soda solution of 1.86 l / h. The residence time of the suspension in the reactor is 30 minutes, the reaction temperature is 35 +, the amount of soda added relative to brine magnesium is 80%, the pH of the pulp is 7.38-7.40. Recovered the slurry suspension of TGCMs is collected in a 2.5 liter mix container.

then filtered under a pressure of 2 atm on a funnel that simulates the operation of the filter press. Number filtered

the precipitate of TPMS with the content of Mg-CC -ЗН О 61, is 0.59 kg / h, the amount of mother liquor is 4.69 l / h of composition, 27. g / l, Ca O, 16 g / l.

The precipitate is washed on a funnel with water.

in the amount of 2.12 l / h then calcined at 6OO-7EP.

You get magnesium oxide in an amount of 0.1O6 kg / h, the content is 92, CaO is 0.2%.

Claims (1)

Claim" A method of producing magnesium oxide from a brine containing magnesium and calcium salts, by contacting the brine with soda, followed by separation of the precipitate from the mother liquor, washing and calcining, characterized in that, with a chain to reduce the content of calcium compounds in the product, soda is fed into 80-85% relative to magnesium in brine and the process is carried out to the stage of washing the precipitate for 3060 minutes.