SU1281508A1 - Method of producing sulfur dioxide from phosphogypsum - Google Patents

Abstract

This invention relates to methods for producing sulfur dioxide from phosphoric gypsum, a waste product in the production of phosphoric acid. The purpose of the invention is to increase. concentrations of sulfur dioxide in the process gas, production of cement for the cement and reduction of energy consumption of the process. According to the method, phosphogypsum (mixed with quartzite and aluminum powder to obtain a uniform mixture with a SiOj / CaO ratio of 0.5-1.0. Aluminum powder is introduced in an amount of 5-10 wt.%. The mixture is granulated; thermally dehydrated to the residual humidity 0.01-0.05 wt.%, followed by desulfurization with the passage of electric current through the melt. Decomposition level 97.2-99.9%, concentration 80, in gas 70-90%. 1 tab. Ct & (P c

Description

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The invention relates to chemical technology of inorganic substances, in particular, to methods for producing sulfur dioxide from phosphogypsum — a waste product of the production of phosphoric acid in sulfuric acid treatment of apatites and phosphorites.

The purpose of the invention is to increase the concentration of sulfur dioxide in the process gas, to produce a cement slurry and to reduce the energy consumption of the process.

The method is performed in a sluggish manner.

Phosphogypsum is mixed with quartzite aluminum powder to obtain a uniform mixture with a ratio of 5-1.0. The mixture is granulated on a plate granulator and thermally ehydrated to a residual moisture content of 0.01-0.05 wt.% At 650 ° C. After that, the granules are fed to the electric arc furnace, where the charge melts at 1300 ° C and is desaturated under conditions of electric current passing through the melt. The degree of decomposition of the mixture, 9%. The resulting process gas contains 75-90% SO2, and the slag that is drained from the furnace is a cementing agent with high hydraulic activity. Carrying out the process under the specified conditions lowers the melting temperature of the charge, reduces the decomposition time to 15–20 minutes, reduces energy consumption by 2.0–3.5 times and the consumption of electrode material by 2–7 times.

Example 1. Phosphogypsum in an amount of 100 kg is mixed with 24.34 kg of quartzite and 6.22 kg (5%) of aluminum powder to obtain a uniform mixture with a Si02 / CaO ratio of 0.65. The resulting mixture is granulated on a plate granulator and dehydrated to a residual moisture content of i 0.05 wt.%. The granules are fed to the electric arc furnace where the melting and desulfurization of the charge takes place. The concentration of sulfur dioxide in the released process gas is 75 vol.%. The cost of electricity compared to a bristle that does not contain aluminum is reduced by 2 times, the consumption of the electrode is 2.5 times. The melting time of the charge 20 min. Phase composition in the slurry,%: 2CaO SiOij 70, CaO-SiO, 15, Qj 15. The strength of the resulting cement is 52.2 MPa.

2. Phosphogypsum in kg

Example

As a weight, 100 kg is mixed with 30, quartzite and 10.41 kg (8%) aluminum powder to obtain a uniform mixture with a ratio of SiO / CaO-0.8. The mixture is granulated on a plate granulator and dehydrated to a residual moisture of 0.05%. The dried granules are decomposed in an electric arc furnace to produce a process gas containing 90% by volume of sulfur dioxide. The cost of electricity for decomposition is reduced by 2 times in comparison with the mixture that does not contain aluminum, the consumption of electrode is 6 times lower. Brem melting 17 min. Phase composition in the slider,%: 60, CaSiO 20, CajAtjO, - -

20. The strength of the cement produced is 45.4 MPa.

Example 3. Phosphogypsum in an amount of 100 kg is mixed with 37.81 kg of quartzite and 13.78 kg (10%) of aluminum powder to obtain a uniform mixture with the α-ratio, 0. After that, the mixture is granulated on a plate granulator and dehydrated to a residual moisture content of 05%. The dried mixture is decomposed in an electric arc furnace to produce a process gas containing 85% by volume

sulfur dioxide. The cost of elaptic energy for decomposition, as compared with the mixture, which does not contain aluminum, is reduced by 3 times, the consumption of electrodes - by 7 times.

The time of complete decomposition of the mixture is 15 min. Phase composition in the slurry,%: Ca SiO 40, CaSiOg 35, Ca2A1.0 25. The strength of the obtained cement is 40.1 MPa,

The table provides examples of the method.

The content in the charge of aluminum less than 5 wt.% Leads to a decrease in the concentration of sulfur dioxide in the gas and the intensity of the process, an increase in energy consumption and a greater consumption of electrode material. The aluminum content of more than 10 wt.% Contributes to the formation of sulphides (CaS, A1 Sj) in the melt, worsening the technical and economic performance of the process and facilitating the flow of secondary reactions, reducing DJ; their degree of desulfurization, as well as making the manufacture of cements from slags.

Upon decomposition of CaSO2, oxygen is bound to aluminum, which protects the electrode from corrosion.

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and leads to an increase in the concentration of SiOj / CaO 0.5-1.0, granulation of the mixture and SO2 in the gas. Formed in melted thermal dehydration to the remaining CaO and form silicates with silica humidity of 0.01-0.05 wt.% With mom silicates, which leads to a reduction in the subsequent desulfurization of the electrolyte decomposition time, as well as 5 arc-arc furnace under the conditions of passage that in the cementing properties of slags on the electric current through the melt, the level in the cement properties of Portland cement is different in that with brand 400-500. The aim is to increase the concentration of sulfur dioxide in the process gas, according to formula of the invention of a cement mortar and a reduction in the cost of the process, in non-

The method of producing sulfur dioxide from the batch mixture is injected with a powder of metal-phosphogypsum, which includes the mixing of fosic aluminum in the amount of 5-gypsum with quartzite to a ratio of 10 wt.%

Table continuation

Claims (1)

Claim A method of producing sulfur dioxide from phosphogypsum, comprising mixing phosphogypsum with quartzite to a ratio SiO ₂ / CaO = 0.5-1.0, granulation of the mixture and its thermal dehydration to a residual moisture content of 0.01-0.05 wt.%, Followed by desulfurization in an electric arc furnace under conditions of electric current passing through the melt, characterized in that , in order to increase the concentration of sulfur dioxide in the process gas, obtain a cement binder and reduce the process’s electrical consumption, 510 wt.% aluminum metal powder is introduced into the initial charge m = _SiO_2 Sub Content M wt.% Electricity consumption, kWh / t h _s so ₄ Electrode consumption, kg / t H „SO, 2 4 The decomposition process, min Degree of decomposition, d, % Concentration S0 ₂ ,% 1 2 3 4 5 6 7 0.50 0 5080 100.0 40 97,20 60.0 0.50 5 2540 48.8 22 99.90 75.0 0.65 0 41.65 70.0 38 97,20 70.0 0.65 2 3980 65.0 35 97.60 70.0 0.65 5 2070 28.5 20 99.90 75.0 ’ 0.65 8 1660 20,0 18 99.90 78.0 0.65 10 1225 18.0 16 99.90 90.0 0.65 thirteen 2400 26.1 24 70.40 66.0 0.80 0 3200 48.0 37 96.80 70.0 0.80 2 3000 40,0 thirty 97.60 Wo oh 0.80 5 1760 11.1 20 99.90 76.0 0.80 8 1520 7.5 17 99.90 90.0 0.80 10 1100 6.6 ^thirteen 99.90 86.0 0.80. ^thirteen 2220 27.6 26 76.10 65.0 1.00 0 3100 45.0 28 98.97 60.0 100 2 3000 40,0 26 99.00 70.0 1.00 5 1540 11, 0 18 99.90 75.0 Table continuation. 1 2 3 4. . '' 5 6 7 1.00 8 1230 8.6 fifteen 99.90 80.0 1.00 10 1050 6.2 fifteen 99.90 85.0 1.00 thirteen 2180 26.8 26  76.60 55.0