A method of obtaining a pigment containing chromium phosphate

 

(57) Abstract:

The invention relates to methods for pigments containing chromium phosphate, used in the paint industry. The method of producing pigment includes interaction feedstock containing bichromate alkali metal with phosphoric acid and the reducing agent is a sulfite or sodium thiosulfate in the presence of sulfuric acid. As a source of raw materials use of waste water disposal of solid waste cleanup carbide acetylene containing, wt.%: CR6+in terms of PA2CR2O70,8-4,0, chromium phosphates of 2.5-3.5, bisulfate chromium 15,0-16,0, sulfuric acid of 1.5-2.0. Waste water has a pH of 3-3 .5 and a temperature of 40-50oC. Phosphoric acid with a mass concentration of 85% charge in the amount of 12.4-21,3% vol. in relation to the original waste water. The reducing agent is sodium sulfite charge in the amount of 6.0-29,0 wt. % of either sodium thiosulfate take in the amount of 2.0 to 10.0 wt.% in relation to the original waste water. The technical result of the invention is the recovery of valuable components from waste water to obtain an anticorrosive pigment, reduce wastewater toxicity, as well as reducing the duration of the process. table 1.

Known methods for producing pigments based on chromium phosphate by reacting commodity chromiferous products with phosphoric acid in the presence of organic reducing agents of different nature (A. C. the USSR 589244, class C 09 C 1/34, 25.01.78, BI-1). However, the process of obtaining pigment long and allows you to get the pigment only for primer.

Closest to the claimed invention is a method for anticorrosive pigment of the trademark chrome-containing products and phosphoric acid at pH 2.8 to 3.5 using as a reducing agent of sodium sulfite or sodium thiosulfate and the aging pigment for 40 min at 95-100o(Belenky, E. F., Raskin I. C. Chemistry and technology of pigments).

However, in the process accumulating a large amount of chromium wastewater. The process of obtaining long as it includes the stage of preparation of a solution of Na2Cr2O7+H3PO4and the solution of reducing agent at a temperature of 40oC.

An object of the invention is the recovery of valuable components from waste water to obtain an anticorrosive pigment, reduce wastewater toxicity, and C is NTA, containing chromium phosphate, including the interaction of bichromate alkali metal with phosphoric acid and the reducing agent is a sulfite or sodium thiosulfate in the presence of sulfuric acid, what is new is that the quality of raw materials use of waste water disposal of solid waste cleanup carbide acetylene containing, wt.%:

Cr+6in terms of Na2Cr2O7- 0,8-4,0

Phosphate chromium - 2,5-3,5

Bisulfate chromium - 15,0-16,0

Sulfuric acid - 1,5-2,0

having a pH of 3-3 .5 and a temperature of 40-50oWith phosphoric acid (with a mass concentration of 85%) take in the amount of 12.4-21,3% vol. in relation to the source of waste water; the reducing agent is sodium sulfite - take in the amount of 6.0-29,0 wt.% (or sodium thiosulfate take in the amount of 2.0 to 10.0 wt.%) in relation to the original waste water.

Wastewater specified structure are formed at the disposal of solid waste generated in the production of acetylene carbide method and have a temperature of 40-50oC.

A relatively high concentration (in the range of 5-12 wt.%) total chromium in the effluent allows the process of its recovery; acidic with a pH of 3-3 .5. due to the presence of residual sulfuric acid, spacesa is necessary to determine the concentration of CR6+and total chromium in water; to calculate the necessary amount of reducing agent on the residual content of not reacted in the primary process CR6+and the dose of phosphoric acid with a concentration of 85 wt.% in the ratio of 1:1 to the total chromium. In the reactor with agitator pumping waste water with a temperature of 40-50oWith, pour the required amount of phosphoric acid with a concentration of 85 wt.% and with active stirring asleep calculated dose reductant. Released heat helps for the formation of chromium phosphate and the formation of the pigment particles in the process of aging.

Example 1. To 100 ml of wastewater with a temperature of 40oWith, contains, wt.%

Cr+6in terms of Na2Cr2O7- 0,8

Phosphate chromium - 3,5

Bisulfate chromium - 15,0

Sulfuric acid - 1,5-2,0

and having a pH of 3-3 .5 add to 12.4 ml of phosphoric acid with a concentration of 85 wt.% and 6 g of sodium sulfite (Na2SO37H2About). The reaction of lead within 20 minutes, followed by aging at a temperature of 85-95oC for 30 minutes the Precipitate is filtered, washed and dried. The mass of the obtained pigment 10,3,

Example 2. For example, 1 to 100 ml of wastewater with a temperature of 40-50oWith, contains, mA 6,0

Sulfuric acid - 1,5-2,0

and having a pH of 3-3 .5 add to 21.3 ml of phosphoric acid with a concentration of 85 wt.% and 29 g of sodium sulfite. The mass of the obtained pigment 28,6,

Example 3. In example 1, but in use as a reducing agent sodium thiosulfate in number 2, the Mass of the obtained pigment 11,5,

Example 4. In example 2, but in use as a reducing agent sodium thiosulfate in an amount of 10 g mass of the obtained pigment, 30,2

Anticorrosive properties of the obtained pigment was identified in the study compositions indicators: water absorption, resistance and kislotnosti. For preparation of compositions in natural drying oil was administered to 25 wt.% a mixture of pigment chalk in the ratio of 1:1. The prototype is represented by a composition based on natural drying oil-modified mixture of commercial chrome pigment chalk in the ratio indicated.

The results are given in the table.

Analysis of the results suggests that the resulting pigment has anti-corrosion properties compared to the standard pigment. The acid test samples after 120 hours of exposure is almost twice as high standard.

In addition to topsurface sodium. Therefore, further processing of sewage enterprises may be conducted jointly with other acidic or alkaline wastewater, or after appropriate dilution of the effluent may be discharged into sanitary sewers. When implementing the method, the output of the pigment containing phosphate chromium is 80-250 kg per 1 m3wastewater specified structure.

Thus, the proposed method allows you to extract valuable components from the waste water to obtain a pigment having anti-corrosion properties, and to reduce the toxicity of the wastewater.

A method of obtaining a pigment-containing phosphate of chromium, including interaction feedstock containing bichromate alkali metal with phosphoric acid and the reducing agent is a sulfite or sodium thiosulfate in the presence of sulfuric acid, characterized in that the quality of raw materials use of waste water disposal of solid waste cleanup carbide acetylene containing, by weight. %:

CR6+in terms of PA2CR2O7- 0,8-4,0

Phosphate chromium - 2,5-3,5

Bisulfate chromium - 15,0-16,0

Sulfuric acid - 1,5-2,0

having a pH of 3-3 .5 and a temperature of 40-50oWith phosphoric acid mass is t sodium take in the amount of 6.0-29,0 wt. % of either sodium thiosulfate take in the amount of 2.0 to 10.0 wt. % compared to the influent wastewater.

 

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