SU1527168A1 - Method of producing sodium chromate - Google Patents

Abstract

The invention relates to chemical technology and simplifies the process, reduces the cost of the target product, and produces sludge suitable for the production of refractory materials. The method of producing sodium chromate from ferrochrome is that raw magnesite with a CAO content of not more than 2.8 wt.% And SIO ₂ not more than 2.4 wt.% Is used as a filler. 2 tab.

Description

one

(21) A189642 / 23-26

(22) 12/10/86

(46) 12/07/08. Number 45

(75) GD Mazalehschy, B.A. Pakhomov,

A.A. Chertkov, I.Ya.Kashirska,

V.Ladygin and V.P.Sorokina

(53) 661.876.231 (088.8)

(5b) USSR author's certificate

 1142448, cl. C 01 G 37/14, 1979.

(54) METHOD FOR OBTAINING SODIUM CHROMATE (57) The invention relates to chemical technology and allows to simplify the process, reduce the cost of the target product, and obtain sludge suitable for the production of refractory materials. The method of obtaining sodium chromate from ferrochrome is that raw magnesite with a CaO content of not more than 2.8 wt.% And SiO no more than 2.4 wt.%, Table 2 is used as a filler.

The invention relates to chemical technology, in particular to the preparation of sodium chromate from ferrochrome, and can be used in the production of chromium compounds.

The purpose of the invention is to simplify the process, reduce the cost of the target product and obtain sludge suitable for the production of refractory materials.

The method is carried out as follows.

Carbon ferrochrome and raw magnesite, after control drying, are ground in ball mills to a brittleness of 0.083 mm. Then, these materials are blended in the required ratio together with soda ash and the mixture is subjected to oxidative roasting at. The roasting product (sinter) is subjected to water leaching at W: T 1.25-1.75 at C-C on the principle of countercurrent with three filtration and two repulphates. As a result, chromate liquors are obtained, which, after their purification from silicon and aluminum impurities, become commercially known methods, and sludge, which after drying with semi-calcined magnesite, is suitable as a raw material for the manufacture of high-quality natural magnesite refractories.

The raw magnesite of CM-I - CM-3 grades is used as a filler of baked shchychit. In tab. 1 shows the brand of raw magnesite.

The decisive factor in selecting magnesite grades as a filler for the gihty is the content of CaO and SiOj impurities, which are undesirable both when processing the charge with magnesite on sodium chromate and for using the resulting slurry in refractory production, therefore the magnesite grade CM 4 in its composition (CaO 6 6 7.0 wt.%) Is unsuitable for the proposed method.

with s

cl

ate IND

35

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Example I, A material containing 1A May, h, carbon ferrochrome (70.7 wt.% Cr; 9 wt.% C; 0.2 wt.% Si; 0.1 wt.% Iron) is prepared from threshing materials. 21 wt.% Of soda (Q9 wt.%,) And 65 May, h, magnesite grade SM-1 1 (97.4 wt.% MgOOj; 0.8 wt.% 0.3 mln.% 0.6 wt. % CaO;

0.5 wt.% Fe.) 1 Chichtu in the amount of 100 ac, Cho is calcined at 1000 C for 30 minutes in air atmosphere. At the same time, the field is from 66.8 May, h, cake, content, wt.%: CrO, ( general)

28.5; CrOj (water-soluble) 25.7 The obtained sinter is treated with water at L: T 1.75 under conditions of rubbing, in a solution of sodium chromate obtained, g / l: CrO ,, 147; NaOH 3; 3.1; 0.16 „Amount of sodium chromate in terms of 27.8 May„ h,

As schlama after eushki receive 37 May, h. semi-calcined magnesite, containing, wt%: MgO 81.4; CgP5 (water soluble) 0.04; , 3.9; , 11.7; SiO 0.6; 0.3; CaO 1.0- Na 3.38,

A mat of this quality is suitable for obtaining high-quality gees for magnesite and chromium-dyes, refractories instead of brucite. Its yield per conditional ton of sodium chromate is 1.45 tons with a specific consumption of raw magnesite 2.55 g

PRI me R 2 Prepare a mixture containing 10 May and 5 carbon-bearing ferrochrome, 15.5. soda (compositions shown in example 1) and

74.5 mae, hours, magnesite CM-2 (94.5 wt.% M: PO; 1.5 wt.% 0.5 wt.% 1.2 maso of CaO; 1.36 wt.%). The mixture as 00 May, h, is burned at 1000 ° С for 30 minutes in an air atmosphere. At the same time receive

62.6 May, h, bake containing, wt.%: CrO, (total) 21.6; CrO (water soluble) 19.5. Spec was treated with water at W: T 1.25. The sodium chromate solution contains, g / l: CrO, 155; NaOH 2.0; SiOj 8.9; AljOg 0.3. The amount of sodium chromate in solution in terms of Na2.04.

19.7 May, h

41.2 May are obtained as sludge after drying, h „sweat / calcined magnesite containing, in wt.%: MgO

Q

,

g

)

81.4; CrOJ (water soluble) 0.03; , 2.5; Fe2.03 9.2; SiOj 1.1; , 1.0; CaO 2.26; 3.19,

Magnesite of this quality is suitable for producing high-quality magnesites and chromo-magnesite refractories instead of brucite. Its yield on a conditional ton of sodium chromate is 1.671 kg CrOj) 2.3 tons with a specific consumption of raw magnesite 4.1 tons,

Pr 3, Prepared a mixture of May 11, h, ferrochrome, 17.0 May, h, soda and 72 May, h, magnesite grade SM-3 (90.3 May.% MgCO,; 2.2 wt, % SiO.2; 2.4 wt.% CaO). The mixture is treated similarly with -1amera and 2, the resulting specs contains,.%: CrO, (total) 22,9; CrO (water soluble) 20.6. The specter is treated with water at W: T 1.25. The sodium chromate solution contains, g / l: CrO j 153; NaOH 2,3; SiOi 9.4; , 0.26, The amount of sodium chromate in solution in terms of Na ,, CrO. 1.8 May, h

40.4 mA are obtained as sludge after drying. Half-calcined magnesite, containing, in May.%: MgO 30.4; CrO. Water; soluble) 0.03; Oguo 2.78; 9.8; SiO 1.0; A1, 0h 0.9; HPO 3,5; Cao 4.0. Magnesium of this quality is suitable for use of natural magnesites and chromo-magnesite refractories instead of brucite. Its yield on the conditional ton of sodium chromate (671 kg of CgOz) is 2.0 tons with a specific consumption of raw magnesite 3.56 tons.

From the examples given, as a result of the oxidative roasting of the mixture obtained by the proposed method and the subsequent hydro-processing of the resulting cake, the desired product is obtained — a solution of sodium monochromate and a solid residue — sludge (Table 2), which is semi-calcined magnesite, depleted in silicon and doped with chromium and iron oxides, which allows its use in the production of refractory materials. The use of the proposed method significantly simplifies the technological process, n becomes co-current, it eliminates the need for organization recycle filler (countercurrent process in the known method) as compared with the known method cost hroma5 1

This sodium produced by the proposed method decreases because it eliminates the cost of returning the filler to the oxidation roasting mixture (transportation costs, costs for dosing, filtration, sludge drying, etc.), which are almost entirely related to the sodium chromate product.

The consumer cost of semi-calcined magnesite is more substantial than the original raw magnesite in refractory production. The cost of such low-silicon semi-calcined magnesite will be much lower than the cost of the purest SiO content.

Table 1

Components Content of components, wt%, in magnesite grade CM-1 CM-2 CM-3 I CM-A

MgO gg 46.0 ggD5.0 43.0 3-39.0 Cao 0.8: g1.2, 8 7.0 SiO 1.2 1.5 2.4 2.4

Table 2

Sludge content of components, wt.%

way 1-jjтj /

MgO CrjO, j SiO. , j CaO NiO

The proposed 80-82 2.5-3.9 9.2-11.7 0.6-1.2 0.5-1.0 1.0-4.3 Known To 0.5 3.0-4, 0 90.0 SiO +, 4.0-5.5 No 1.0

27168

Claims (1)

natural and unfired magnesium-containing raw material - brucite. Claims method for producing sodium chromate from ferrochrome, including oxidizing roasting of a mixture containing carbon ferrochrome, soda ash and filler, leaching 10 sinter, separation of sodium chromate and sludge, characterized in that, in order to simplify the process, reduce the cost of the target product and obtain sludge suitable for the production of refractory materials, magnesite with a CaO content of not more than 2.8 wt.% Is used as a filler. and SiOi is not more than 2.4 wt.%.