SU1521717A1 - Method of obtaining magnesium oxide - Google Patents

Abstract

The invention relates to methods for producing magnesium oxide from chlorine magnesium solutions and allows increasing the degree of extraction of magnesium, the degree of purity of the regenerated solution, and intensifying the process. The method is carried out as follows. Magnesium hydroxide is precipitated from chlorine-magnesium solutions by treatment with monoethanolamine (MEA), the precipitate is separated by filtration, washed and calcined to produce magnesium oxide. The magnesium solution after separation of the precipitates is treated with electric silk in order to regenerate monoethanolamine by the reaction of RNH ₂ ^. HCL + HCL + NAOH = RNH + NACL + H ₂ O. The mixture is further subjected to separation by distillation at 111-126 ° C. A pure MEA and NACL precipitate are obtained. The magnesium recovery rate is 95.7-97.5%, the recovery rate of the MEM is 95-99%. 1 hp f-ly, 3 tab.

Description

The invention relates to methods for producing oxides of alkaline earth metals and can be used in the chemical industry for the production of magnesium oxide.

The purpose of the invention is to increase the purity of the regenerated monoethanolamine, to increase the degree of magnesium recovery and to intensify the process.

Example. 100 kg of the original chlorine solution containing, in wt.%: MgCla 27.87; CaCb 0.76; NaCl 1.94; KCl 0.82, treated with 100 kg of recycled regenerated. monoethanolamine (MEA) at room temperature and stirring for 40 min. The precipitate obtained is separated from the mother liquor on a vacuum filter and washed with water. After calcining the resulting paste containing 20% Mg (OH) 2 and 80% H2O, 11.44 kg of magnesium oxide with a purity of 100% is formed at 500-550 ° C. The degree of extraction of magnesium from the solution is 97.4%.

183.43 kg of stock solution containing, in wt.%: RNH2 35.49; RNH., HCI 30.4; MgCb 0.39; CAL 0.41; NaCl 1.06; KCl 0.45, mixed at room temperature with 272 kg of electrolytic liquor containing wt.%: NaOH 10.08; NaCl 14.83; H2O 75.09, which is a 20% excess of NaOH from stoichiometry. Obtained after regeneration, the solution containing, wt.%: RNH2 22; NaCl 17.03; KCl 0.18; NaOH 0.75; H2O 60.04, is fed to the rectification, resulting in the formation of 272.86 kg of water and 181.62 kg of a suspension of salts in a liquid mono-ethanol mine.

76.25 kg of liquid monoethanolamine is separated by filtration from 105.37 kg of sediment containing, in wt.%: NaCl 73.45; NaOH 3.24; KCl 0.77; RNH2 22.54. The precipitate is dried, thus receive 82.87 kg of dry sediment and 22.5 kg of monoethanolamine vapor. The degree of distillation of monoethanolamine from the wet sediment is equal to 94.7%. The condensed monoethanolamine is mixed with the filtrate and

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served on the deposition of Mg (OH) 2. The loss of monoethanolamine in the cycle is 1.25%.

In tab. 1 shows the increase in the purity of the target product compared to the prototype. The experiments were carried out at a mass ratio of the initial chlorine-magnesium solution: precipitating monoethanolamine 1: 1; At each washing stage, the mass ratio between the wet Mg (OH) 2 precipitate and the wash water is 1: 1.

In tab. Figure 2 shows data showing an increase in the degree of extraction of magnesium depending on the ratio between the initial chlorine magnesium solution and the regenerated monoethanolamine. Monoethanolamine was regenerated by 100% due to the introduction of 150 wt.% Calcium oxide of the prototype or 120% sodium hydroxide from the stoichiometrically required amount in this method.

In tab. 3 shows the degree of regeneration of monoethanolamine, depending on the amount of reagent used - sodium hydroxide by the proposed method or the lime of the prototype.

As follows from the tables, the use of electrolytic liquor instead of lime makes it possible to increase the degree of extraction of magnesium from 92.8-95.5 to 95.7-97.5%, the degree of regeneration of monoethanolamine from 83--96 to 95-99%.

In addition, the regeneration of MEA by electrolytic lye proceeds much faster (almost instantly), while in the prototype the duration of the process is 40 minutes.

Claims (2)

1. A method of producing magnesium oxide from chlorine magnesium solutions, including precipitating magnesium hydroxide with monoethanolamine, separating the mother liquor precipitate, washing it and calcining to obtain the desired product, regenerating monoethanolamine from the mother liquor by treating it with an alkaline reagent, characterized in that, in order to increase the purity of the regenerated monoethanolamine, the increase in the degree of extraction of magnesium and the intensification of the process; the regeneration of monoethanolamine is carried out by electrolytic liquor, followed by Niemi resulting mixture. 2. The method according to claim 1, differs from the fact that the liquor consumption is 116-120% of stoichiometry. Pure monoethanolamine RNHa 98-100 2-0 Thief Regenerated NaOH: RNH 95.9 NaOH 0.60 NaCl 2.4 KCl 0.15 0.95 H, 0 Regenerated by the news: Rnhj. Y, 25 SAS1g 14.77 NaCl 5.60 23.42 a b and c a 1 93.62 97.06 98.67 99.40 90.33 95.46 97.93 99.07 68,983.29 91.81 96.19 The ratio of the initial solution; circulating monoethanolamine 1: 0.67 1: 0.8 1: 1 1: 1.1 Extent-by-offer method for the magnesium method 95.7 97.0 97.4 97.5 in the solid phase % According to the prototype 92,8 94,6 95,4 95,5 Table 3 Norm reagent,% of stoichiometries100 110, 116 118 120 130 140 150 Degree of rege; non-rotation,% method 89.1 97 99.2 99.7 100 100 100 100 The prototype77, 3 84,7 88,2 89,3 90,5 95,3 99,2 100 ABOUT table 2