RU2472756C1 - Method of producing gypsum binder - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing gypsum binder. The method of producing gypsum binder by dry processing of starting material which is phosphogypsum and/or gypsum rock and a modifying additive, involving mixing, heat treatment and grinding the starting material under the action of an external alternating electromagnetic field in the frequency range of 10-1000 Hz with field strength of up to 100 kA/m in the presence of magnetic-susceptible granular filler with further separation of the obtained dry powder into gypsum binder and magnetic-susceptible granular filler.

EFFECT: high quality of the obtained product, simple technique of production and low power consumption.

11 cl, 7 tbl, 7 ex

Description

The invention relates to a method for producing a gypsum binder, for example grades Г- (2-16) by processing phosphogypsum dumps formed as a by-product of the production of phosphoric acid from apatite and phosphorite raw materials and formed on the basis of the functioning of technological complexes for producing mineral fertilizers, or by processing gypsum stone. Joint processing of phosphogypsum and gypsum stone is also allowed. This invention can be used in industrial inorganic chemistry, the construction industry and the mineral fertilizer industry. The operation of mineral fertilizer enterprises is accompanied by the formation of large-tonnage waste, the volume of which reaches tens of millions of tons. The use of phosphogypsum waste in the manufacture of products of the construction industry and for the production of building gypsum is one of the promising directions in the utilization of the most massive type of enterprise waste.

The patent and technical literature describe many methods for producing a gypsum binder by processing natural raw materials or production wastes containing calcium sulfate, in particular from phosphogypsum, gypsum stone.

So known is a method of producing a gypsum binder from natural raw materials, for example, from phosphogypsum, by separating solid particles from a dust-air mixture in a dust collecting unit at a temperature of 160-190 ° C [RU 2302395, publ. 07/10/2007]. The known method is quite complicated in hardware design.

A method for producing a binder material (cement, lime, gypsum) is described, including obtaining, for example, a cement-air mixture in a spray chamber, followed by shaking and stirring under the influence of an alternating electromagnetic field in a chamber made of a dielectric equipped with electrodes that create an alternating electromagnetic field, performing shaking and mixing due to vortex flows and vibration of the electrodes due to their electromagnetic effects [RU 2366510. publ. 03/12/2008]. The method is quite complicated in technological design, requiring the use of a device with a special electrode design, the need to use a dielectric chamber, and, as a result, a complex control process and low productivity.

There is also known a method of producing a gypsum binder, which consists in heat treatment of gypsum stone by irradiation with an electromagnetic field of a microwave [RU 2040498, publ. 07/25/1995]. The method has the same disadvantages.

A known method of producing a gypsum binder, which is accepted by the authors as a prototype, including mechanical crushing, dehydration (heat treatment) of gypsum with a size of pieces from 10 to 500 mm in an electromagnetic field of ultrahigh frequency and subsequent grinding of the hemihydrate in a ball mill [RU 2023699, publ. November 30, 1994]. The known method is also complicated in hardware and is characterized by multi-stage.

The objective of the present invention is to simplify the method and increase the productivity of the process of obtaining gypsum binder, reduce energy consumption, as well as the disposal of phosphogypsum dumps.

The problem is achieved by the proposed method for producing gypsum binder by dry processing of gypsum-based feedstock, including grinding and heat treatment using an electromagnetic field, characterized in that according to the invention, the feedstock, which is phosphogypsum and / or gypsum stone and a modifying additive, is mixed, followed by heat treatment and grinding under the influence of an external alternating electromagnetic field in the frequency range from 10 to 1000 Hz at STI to 100 kA / m in the presence of magnetism granular aggregate with a further division of the thus obtained dry powder to the gypsum binder and granular aggregate magnetism.

To generate electromagnetic fields, a solenoid type inductor is usually used, capable of generating sinusoidal alternating electromagnetic fields.

Preferably, barium ferrite granules are used as the magnetically susceptible granular filler (granulate).

Mostly barium ferrite is used, containing a binder, for example, γ-Al ₂ O ₃ in an amount up to 60 wt.%.

Barium ferrite granules can be coated with a protective sheath made of metallic and non-metallic materials, for example, X18H10T stainless steel, aluminum, duralumin, fluoroplastics, or polyurethanes.

The processing process is carried out mainly with a volume ratio of magnetically susceptible granular filler to the feedstock equal to 1: (0.2-10), at a temperature not exceeding 190 ° C and a pressure of not more than 10 atm.

As a modifying additive mainly used, for example, slaked and quicklime, ground limestone, cement, in an amount of not more than 5 wt.%. in relation to phosphogypsum or gypsum or a mixture thereof.

The process of mixing, heat treatment and grinding of the feedstock can be carried out sequentially one after the other in different devices, as well as in the same device simultaneously in continuous mode.

The process of processing feedstock in a continuous mode is carried out at a specific feed rate of feedstock of not higher than 50 kg / h per liter of reaction volume.

Carrying out the process in a continuous mode is more technologically advanced on an industrial scale due to the lack of stages of switching modes, stability of parameters, expanded ability to automate and control the process, minimizing manual labor.

The main advantages of the method are the ability to combine and combine in one stage the processes of coarse and fine grinding, as well as heat treatment of the feedstock while maintaining high productivity and high quality of the resulting product. Moreover, due to the use of magnetically sensitive granular filler and variable magnetic fields, there is no need to use movable structures such as rotary kilns. Due to the one-stage, lower degree of heat loss, specific energy consumption is reduced.

The technical result is a simplification of the implementation of the process in the technological execution of obtaining gypsum binder, the implementation of hardware one-stage, increasing the productivity and quality of the target product, as well as reducing energy costs.

The invention meets the criterion of "novelty", as in the well-known scientific, technical and patent literature there is no complete set of features characterizing the invention. The invention also meets the criterion of "inventive step", since there is no information on the production of a gypsum binder in the presence of a magnetically susceptible granular filler, and this does not follow for the specialist explicitly from the prior art for the possibility of its use in the proposed process.

The invention is industrially applicable, so it can be used in industrial inorganic chemistry, the construction industry and the mineral fertilizer industry.

In general terms, the process of obtaining a gypsum binder is carried out as follows.

The initial phosphogypsum, gypsum stone, or a mixture thereof, as well as a modifying additive (modifier) are continuously fed into the electromagnetic processing reactor (REMO) by screw feed. The pressure in the reaction chamber is maintained at a level not exceeding 10 atm, and a temperature not exceeding 190 ° C. REMO contains a magnetically susceptible granular filler (granulate) encapsulated in a shell of metallic or non-metallic materials. The shell thickness is 2-5 mm. The average equivalent diameter of the granules is 5-10 mm. The material flow of phosphogypsum, gypsum, modifier and magnetically susceptible granular filler (granulate) is mixed at the entrance to the REMO. After that, an alternating voltage with specified characteristics is applied to the input of the inductor. At the exit from the REMO, the gypsum binder and the magnetically susceptible granular filler are separated on the filter, which is an integral part of the REMO construct.

The invention is illustrated by specific examples, not limiting its scope.

EXAMPLE 1

As raw material, FOSFOGIPS TU 113-08-418-94, obtained from apatite concentrate by the dihydrate method (meleuz), is used. Appearance - grayish-white crystalline mass.

The chemical composition of phosphogypsum Phosphogypsum in the form of CaSO ₄ - 92.28% No pp Indicator Mass fraction,% one CaO 39,4 2 SO ₃ 53,4 3 MgO 0.08-0.26 four P ₂ O ₅ , including water solution. 0.94, including water solution 0.25-1.2 5 H ₂ O total 30.0-45 6 H ₂ O crystal 19.0-20.0 7 F 0.30 8 Na ₂ O 0.02-0.2 9 K ₂ O 0.004-0.08 10 SiO ₂ 0.3-1.0 eleven Fe ₂ O ₄ 0.05-0.16 12 Al ₂ O ₃ 0.08-0.2 13 Insoluble residue 0.25 fourteen As 0,0002 fifteen Cu 0.0026 16 Cr 0.00015 17 Cd 0,000081 eighteen Ni 0,0005 19 Pb 0,00007 twenty Rare earth elements 0.57 21 Chlorine Traces

All metal impurities can be in the form of sulfates.

The initial phosphogypsum and limestone are continuously fed through a screw feed into an electromagnetic processing reactor (REMO). The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 30 kg / h per liter of reaction space - 900 kg / h in terms of the entire reactor. The pressure in the reaction chamber is maintained at 1.1 atm, and the temperature is 163 ° C. In REMO there is a granulate of barium ferrite magnetized to saturation, containing 60 wt.% Binder (γ-Al ₂ O ₃ ) and encapsulated in a 40X18H10T stainless steel shell. The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 30 kg of granulate. The material flow of phosphogypsum, limestone and barium ferrite granules are mixed at the entrance to the REMO. The mass ratio of phosphogypsum / limestone is 98/2. After that, a voltage of 380/220 V with a frequency of 50 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m. At the exit from the REMO, the processed phosphogypsum and the magnetically susceptible granular filler are separated on the filter, which is an integral part of the REMO construct. The obtained gypsum binder powder has the following characteristics, presented in table No. 1.

Table number 1 True density, g / cm ³ Bending strength, MPa / (kgf / cm ² ) Compressive strength, MPa / (kgf / cm ² ) Specific surface, ^cm2 / g Setting time, start / end, h Compliance with the brand according to GOST 125-79 2.6 2.8 / (28) 5.1 / (51) 7860 16/27 G5

EXAMPLE 2

As raw material, FOSFOGIPS TU 113-08-418-94, obtained from apatite concentrate of the Kola Peninsula using the dihydrate method, is used. Appearance - grayish-white crystalline mass.

The chemical composition of phosphogypsum: No pp Indicator Mass fraction,% one CaSO ₄ × 2H ₂ O 92.7 2 SrSO ₄ × 2H ₂ O 1.4 3 SiO ₂ 0.8 four CaHPO ₄ 0.2 5 FeHPO ₄ 0.4 6 MgHPO ₄ 0.2 7 Alpo ₄ 0.5 8 H ₃ PO ₄ 0.9 9 CaF ₂ 0.4

The initial phosphogypsum and limestone are continuously fed through a screw feed into the electromagnetic processing reactor REMO. The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 40 kg / h per liter of reaction space - 1200 kg / h in terms of the entire reactor. The pressure in the reaction chamber is maintained at 1.3 atm, and the temperature is 170 ° C. The REMO contains granules of barium ferrite magnetized to saturation, containing 50 wt.% Binder (γ-Al ₂ O ₃ ) and encapsulated in a 40X18H10T stainless steel shell. The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 30 kg of granulate. The material flow of phosphogypsum, limestone and barium ferrite granules are mixed at the entrance to the REMO. The mass ratio of phosphogypsum / limestone is 98/2. After that, a voltage of 380/220 V with a frequency of 50 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m. At the exit from the REMO, the processed phosphogypsum and granulate are separated on the filter, which is an integral part of the REMO construct. The characteristics of the resulting product are presented in table No. 2.

Table number 2. True density, g / cm ³ Bending strength, MPa / (kgf / cm ² ) Compressive strength, MPa / (kg / cm ²⁾ Specific Setting time, start / end, h Compliance with the brand according to GST125-79 surface, cm ² / g 2,5 2.5 / (25) 4.1 / (41) 6370 17/29 G4

EXAMPLE 3

As raw materials, FOSFOGIPS TU 113-08-418-94 is used,

obtained from phosphorite raw materials of Karatau by the dihydrate method.

Appearance - a grayish-white crystalline mass with an admixture of aggregated agglomerates.

The chemical composition of phosphogypsum: No pp Indicator Mass fraction,% one CaSO ₄ × 2H ₂ O 80.5 2 SrSO ₄ × 2H ₂ O not upd. 3 SiO ₂ 17.0 four CaHPO ₄ 0.3 5 FeHPO ₄ 0.3 6 MgHPO ₄ 0.7 7 Alpo4 0.4 8 H ₃ PO ₄ 0.2 9 CaF ₂ 0.2

The initial phosphogypsum and limestone are continuously fed through a screw feed into the electromagnetic processing reactor REMO. The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 50 kg / h per liter of reaction space - 1500 kg / h in terms of the entire reactor. The pressure in the reaction chamber is maintained at 1.2 atm, and the temperature is 165 ° C. REMO contains granules of barium ferrite magnetized to saturation, containing 50 wt.% Binder (γ-Al ₂ O ₃ ) and encapsulated in a 40X18H10T stainless steel shell. The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 30 kg of granulate. The material flow of phosphogypsum, limestone and barium ferrite granules are mixed at the entrance to the REMO. The mass ratio of phosphogypsum / limestone is 99/1. After that, a voltage of 380/220 V with a frequency of 50 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m.

At the exit from the REMO, the processed phosphogypsum and granulate are separated on the filter, which is an integral part of the REMO construct. The characteristics of the resulting product are presented in table No. 3.

Table number 3 True density, g / cm ³ Bending strength, MPa / (kgf / cm ² ) Compressive strength, MPa / (kgf / cm ² ) Specific surface cm ² / g Setting time, start / end, h Compliance with the brand according to GOST 125-79 2,5 1.25 / (12.5) 2.20 / (22) 5130 15/28 G2

EXAMPLE 4

As raw materials, gypsum stone of the Nomovoskovskoe gypsum stone deposit with a CaSO ₄ × 2H ₂ O content of about 90 wt.% And crystallization water is about 19 wt.% (GOST 4013-82).

Appearance - white stones, sometimes with a slight grayish tint, with an average stone size of 3-5 cm.

Gypsum stone and Portland cement ПЦ-400 (GOST 10178-85) are continuously fed into the REMO electromagnetic processing reactor by screw feed. The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 10 kg / h per liter of reaction space - 300 kg / h in terms of the entire reactor. The pressure in the reaction chamber was maintained at 9.2 atm, and the temperature at 165 ° C. In REMO there is a granulate of barium ferrite magnetized to saturation, containing 30 wt.% A binder (γ-Al ₂ O ₃ ) and encapsulated in a 40X18H10T stainless steel shell. The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 37 kg of granulate. The material flow of gypsum stone, Portland cement and barium ferrite granulate are mixed at the entrance to the REMO. The mass ratio of gypsum stone / cement is 95/5. After that, a voltage of 380/220 V with a frequency of 50 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m. At the exit from the REMO, the processed gypsum and granulate are separated on the filter, which is an integral part of the REMO construct.

Characteristics of the resulting product are presented in table No. 4.

Table number 4 True density, g / cm ³ Bending strength, MPa / (kgf / cm ² ) Compressive strength, MPa / (kgf / cm ² ) Specific surface cm ² / g Setting time, start / end, h Compliance with the brand according to GOST 125-79 2,8 1.63 / (163) 6.2 / (62) 9227 7/17 G16

EXAMPLE 5

As a raw material, a mixture of phosphogypsum from example 1 and gypsum stone from example 4 in a ratio of 50/50 is used. This mixture is modified by Portland cement PC-400 (GOST 10178-85).

A mixture of phosphogypsum and gypsum stone with Portland cement PC-400 (GOST 10178-85) is continuously fed into a REMO electromagnetic processing reactor by screw feed. The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 50 kg / h per liter of reaction space - 1500 kg / h in terms of the entire reactor. The pressure in the reaction chamber is maintained at 1.5 ati, and the temperature is 165 ° C. In REMO there is a granulate of barium ferrite magnetized to saturation, containing 30 wt.% A binder (γ-Al ₂ O ₃ ) and encapsulated in a 40X18H10T stainless steel shell.

The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 30 kg of granulate. The material flow of phosphogypsum, gypsum, Portland cement and barium ferrite granulate are mixed at the entrance to the REMO. Mass ratio (phosphogypsum + gypsum stone) / cement - 95/5. After that, a voltage of 380/220 V with a frequency of 50 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m. At the exit from the REMO, the processed gypsum and granulate are separated on the filter, which is an integral part of the REMO construct. The characteristics of the resulting product are presented in table No. 5.

Table number 5 True density, g / cm ³ Bending strength
MPa / (kgf / cm ² ) Compressive strength, MPa / (kg / cm ²⁾ Specific surface cm ² / g Setting time, start / end, h Compliance with the brand according to GOST 125-79 2.75 2.6 / (26) 5.05 / (50.5) 7335 13/21 G5

EXAMPLE 6

As raw materials used phosphogypsum from example 1.

Phosphogypsum and limestone are continuously fed through a screw feed into the electromagnetic processing reactor REMO. The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 30 kg / h per liter of reaction space - 1200 kg / h in terms of the entire reactor. The pressure in the reaction chamber is maintained at 1.5 ati, and the temperature is 190 ° C. In REMO there is a granulate of barium ferrite magnetized to saturation, containing 50 wt.% Binder (γ-Al ₂ O ₃ ) and encapsulated in an aluminum shell. The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 30 kg of granulate. The material flow of phosphogypsum, limestone and barium ferrite granulate is mixed at the entrance to the REMO. The mass ratio of phosphogypsum / limestone is 98/2. After that, a voltage of 380/220 V with a frequency of 1000 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m. At the exit from the REMO, the processed gypsum and granulate are separated on the filter, which is an integral part of the REMO construct.

The characteristics of the resulting product are presented in table No. 6.

Table number 6 True density, g / cm ³ Bending strength, MPa / (kgf / cm ² ) Compressive strength, MPa / (kgf / cm ² ) Specific surface cm ² / g Setting time, start / end, h Compliance with the brand according to GOST 125-79 2,53 1.27 / (12.7) 2.40 / (24) 5505 14/28 G2

EXAMPLE 7

As raw materials used phosphogypsum from example 1.

Phosphogypsum and limestone are continuously fed through a screw feed into the electromagnetic processing reactor REMO. The volume of the reaction chamber is 30 l. The specific productivity of phosphogypsum is 30 kg / h per liter of reaction space - 1200 kg / h in terms of the entire reactor. The pressure in the reaction chamber is maintained at 1.5 ati, and the temperature is 160 ° C. In REMO there is a granulate of barium ferrite magnetized to saturation, containing 50 wt.% Binder (γ-Al ₂ O ₃ ) and encapsulated in an aluminum shell. The shell thickness is 2 mm. The average equivalent diameter of the granules is 5 mm. The reactor contains 30 kg of granulate. The material flow of phosphogypsum, limestone and barium ferrite granulate is mixed at the entrance to the REMO. The mass ratio of phosphogypsum / limestone is 98/2. After that, a voltage of 380/220 V with a frequency of 10 Hz is applied to the input of the inductor, with a field strength in the reaction zone of 95-100 KA / m. At the exit from the REMO, the processed gypsum and granulate are separated on the filter, which is an integral part of the REMO construct.

Characteristics of the resulting product are presented in table No. 7.

Table number 7 True density, g / cm ³ Bending strength, MPa / (kgf / cm ² ) Compressive strength, MPa / (kgf / cm ² ) Specific surface, ^cm2 / g Setting time, start / end, h Compliance with the brand according to GOST 125-79 2,5 2.6 / (26) 4.3 / (43) 6425 16/28 G4

Claims (11)

1. A method of obtaining a gypsum binder by dry processing of gypsum-based feedstock, including grinding and heat treatment using an electromagnetic field, characterized in that the feedstock, which is phosphogypsum and / or gypsum stone and a modifying additive, is mixed with subsequent heat treatment and grinding under the action of an external alternating electromagnetic field in the frequency range from 10 to 1000 Hz at a strength of up to 100 KA / m in the presence of magnetically susceptible granular apolnitelya and subsequent separation of the thus obtained dry powder for gypsum binder and granular aggregate magnetism. 2. The method according to claim 1, characterized in that barium ferrite granules are used as magnetically susceptible granular filler. 3. The method according to claim 2, characterized in that the use of barium ferrite containing a binder in an amount of up to 60 wt.%. 4. The method according to claim 2, characterized in that the granules of barium ferrite are used, coated with a protective shell of metallic or non-metallic materials. 5. The method according to claim 1, characterized in that as a modifying additive mainly use, for example, slaked or quicklime, ground limestone or cement in an amount of not more than 5 wt.%. in relation to phosphogypsum or gypsum or a mixture thereof. 6. The method according to claim 1, characterized in that the processing process is carried out with a volume ratio of magnetically susceptible granular filler to the feedstock equal to 1: (0.2-10). 7. The method according to claim 1, characterized in that the exposure to an alternating electromagnetic field is carried out by an inductor of the solenoid type. 8. The method according to claim 1, characterized in that the processing of the feedstock is carried out at a temperature of not higher than 190 ° C and a pressure of not more than 10 MPa. 9. The method according to claim 1, characterized in that the mixing process, heat treatment and grinding of the feedstock are carried out sequentially one after another in different devices. 10. The method according to claim 1, characterized in that the mixing process, heat treatment and grinding of the feedstock are carried out in one apparatus simultaneously in a continuous mode. 11. The method according to claim 10, characterized in that the process of processing the feedstock is carried out at a specific feed rate of feedstock of not higher than 50 kg / h per liter of reaction volume.