SU1733385A1 - Method for synthesis of alkaline-earth metal molybdates - Google Patents

Abstract

The invention relates to methods for the preparation of alkaline earth metal molybdates and makes it possible to reduce the cost of the process. A portion of cinder or a technical product containing molybdenum trirxide is mixed with an equimolar amount of magnesium oxide in terms of molybdenum trioxide. The resulting mixture is treated at 60-100 ° C with water and a solution of an alkaline earth metal compound is added to the resulting solution of magnesium molybdate. The precipitate of alkaline earth metal molybdate is separated from the solution, washed, dried and analyzed. The yield of the target product is quantitative. The content of the main substance in it is 99.4-99.83%. (Ls

Description

This invention relates to inorganic chemistry, in particular, to methods for producing alkaline earth metal molybdates used as luminophores and bases of laser crystals.

A method of producing alkaline-earth metal molybdates by heat treatment of equimolar amounts of oxides or carbonates of these metals and molybdenum trioxide at 600-700 ° C according to the reaction equations is known.

MeO + MOOS MeMo04, where Me is Ca; Ba; Sr,

MeSO3 + MOOS MeMo04 + C021

A known method for producing alkaline-earth metal molybdates, in particular barium molybdate, by calcining a mixture of sodium molybdate and barium chloride at 640-650 ° C, preferably takes

53.3-57.3 wt.% Barium chloride and 46.7-42.7 wt.% Sodium molybdate, followed by separation of barium molybdate from the cake by grinding and washing sodium chloride with distilled water.

The disadvantages of the known methods are the high cost of the process due to the use of starting reagents of the brand h.ch. and hours, the duration and multistage process.

Closest to the present invention is a method for producing alkaline-earth metals, which includes mixing aqueous solutions of molybdenum compounds (NaaMoO) and alkaline-earth metals (MeCC12 or Me (NO3) 2), separating the molybdates formed, washing and drying them.

The disadvantages of the method are the high cost of obtaining molybdates for

Xi

CO 00

co

using the original components of brand h.ch. and hours and the need for additional purification due to contamination of the target product.

The aim of the invention is to make the process cheaper by using molybdenum containing butts and technical products.

The goal is achieved by those. that according to the proposed method, a calcine or technical product containing molybdenum trioxide is taken, an equimolar amount of magnesium oxide is added, treated in water at 60-100 ° C to form molybdate of magnesium and the subsequent release of alkaline-earth metal molybdates, into a solution of magnesium molybdate of soluble salts of these metals and separating the molybdate obtained from the corresponding metal.

The process is based on reactions

MDO + MOOS MDMOSM0)

MgMo04 + Me (R) 2 iMeMo04 + Mg (R) 2, (2) where Me is Ba; Ca; Sr;

R is ND -c; SG

A temperature of 60-100 ° C is optimal for the Process, since at a lower temperature the process goes very much. slowly, and higher temperatures require special equipment.

The need to use an equimolar ratio of magnesium and molybdenum oxides is associated with the need for complete extraction of molybdenum from butts and technical products. As technical products, a product with a molybdenum trioxide content of 30 and 32% is used. Used cinders contain 93-97% molybdenum trioxide.

The ratio t: l (the ratio of the weight of the solid to the liquid phase) depends on the content of molybdenum in the feedstock. The optimal t: z ratio for the calcine is 1: 8, and for the middling 1: 5.

PRI me R 1. Synthesis of Vamosm. Take 15.34 g of cinder with a molybdenum trioxide content of 93.86% and an equimolar amount of magnesium oxide (4 g),. Aqueous workup is carried out at 60 ° C, insoluble impurities are filtered off. To the resulting solution of mdMoSM with a concentration of 116 g / l, 26.1 g of barium nitrate are added with a content of the main substance of 99.5% in an amount sufficient to completely precipitate barium molybdate. The resulting precipitate of barium molybdate in the amount of 29.52 g with a yield of 99.8% is filtered off, washed, dried. The resulting product contains 99.4% of the main substance

PRI mme R 2. Synthesis of VAMOSM. Analogously to example 1, a calcine and an equimolar amount of magnesium oxide with respect to molybdenum trioxide are taken, water treatment is carried out at 80 ° C until the formation of MDMo04 with a concentration of 117 g / l, which corresponds to the extraction of 9.8% molybdenum from the calcine, is added 20, 7 g barium chloride grade h.ch, The resulting precipitate of barium molybdate

0 in the amount of 29.52 g. The analysis shows the content of the main substance in it is 99.5%. The yield of the target product is 99.9%.

PRI me R 3. Synthesis Samoz. They take 16 g of cinder with a MoO3 content of 94.5% and an equivalent molar amount of MdO (4.2 g), water treatment is carried out at 1: 8 at 90 ° C, and insoluble impurities are filtered out. To the resulting solution of MDMoOZ with a concentration of 119 g / l, 16 g of calcium nitrate mark h is added. The calcium molybdate obtained is obtained, in the amount of 19.88 g is washed and dried. The yield of the target product is 99%, the content of the main substance is 99.83%. As a soluble calcium salt, along with nitrate,

5 calcium chloride and perchlorate may be used.

PRI me R 4. Synthesis of ZgMoSm. As in Example 1, 15.7 g of chloride are added to a solution of MgMoO-q with a concentration of 116 g / l.

0 strontium brand h.ch. The obtained strontium molybdate in the amount of 24.6.5 g is washed and dried, the yield of the target product is 99.8%, the content of the basic substance is 99.83%. As soluble salts of strontium qi for strontium molybdate precipitation, strontium nitrate and strontium perchlorate can be used with a similar result.

PRI me R 5. Synthesis of samoz. Take 18 g of middling containing trioxide

0 molybdenum 30%, equimolar MoO3 amount of magnesium oxide in the amount of 1.5 g. Poured with water at, carried out water treatment at 100 ° C, insoluble impurities were filtered, in the resulting solution of MDMo04 with a concentration of 70.77 g / l 13.23 g of calcium chloride grade h. The obtained precipitate of calcium molybdate in the amount of 7.5 g is washed and dried. Purpose product yield 99%. Content

0 main substance 99.5%.

PRI me R 6. Synthesis of SrMo04. Take 20 g of the intermediate product with a molybdenum trioxide content of 32% and an equimolar amount of MDO (1.7 g), pour water at,

5, the aqueous treatment is carried out at 100 ° C, insoluble impurities are filtered off. 15.73 g of strontium chloride mark H is added to the resulting solution with a concentration of 75.39 g / l. The resulting precipitate of strontium molybdate, in the amount of 11.02 g, is washed.

dried The yield of the target product is 99.5%. Content of the main substance is 99.3%.

The method allows obtaining high purity alkaline-earth metal molybdates in high yield using cinder and technical products (industrial products), which makes it cheaper to produce alkaline-earth molybdates. The method is simple in execution, economical, does not require special equipment.

Claims (1)

Claim method for producing alkaline-earth metal molybdates, comprising mixing aqueous solutions of molybdenum and alkaline-earth metal compounds, separating, washing, and drying the resulting precipitate, characterized in that making the process cheaper, using cinder as the molybdenum compound, the content of molybdenum trioxide, which is mixed with an equimolar amount in terms of molybdenum trioxide and oxide 0, the resulting mixture is treated with water at 60-100 ° C, after which the resulting solution of magnesium molybdate is mixed with an aqueous solution of an alkaline earth metal salt.