Process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate by utilizing metatitanic acid slurry

Abstract

The invention belongs to the technical field of preparation of tungsten-containing catalyst titanium dioxide, and particularly relates to a process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate by utilizing metatitanic acid slurry. The preparation process comprises the following steps: (1) preparing metatitanic acid slurry; (2) preparing an ammonium metatungstate solution; (3) dipping reaction; (4) squeezing and filtering by a plate frame, washing for the first time, circulating and neutralizing ammonia water, and washing for the second time; and (5) preparing tungsten-containing catalyst titanium dioxide and high-purity ammonium sulfate. According to the process for preparing the tungsten-containing catalyst titanium dioxide and co-producing the high-purity ammonium sulfate by using the metatitanic acid slurry, the yield of tungsten is 100%, the comprehensive utilization of energy is realized, and the energy consumption required by production is greatly reduced; the plate-and-frame filter press can be used for continuously filtering, neutralizing and washing, filter cakes do not need to be re-pulped after filtering, continuous operation is achieved, the automation degree is high, productivity is improved, the number of devices is reduced, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing tungsten-containing catalyst titanium dioxide, and specifically relates to a process for preparing tungsten-containing catalyst titanium dioxide by using metatitanic acid slurry and co-producing high-purity ammonium sulfate. Background Art

[0002] Tungsten-containing amorphous titanium dioxide is widely used in the field of catalysts, especially in automobile exhaust denitration catalysts. In the past, it was prepared by physically mixing tungsten-containing solid substances with amorphous titanium dioxide powder. The tungsten-containing catalyst titanium dioxide prepared by this method is prone to uneven mixing of tungsten and titanium dioxide. In addition, titanium dioxide only serves as a matrix and does not play a synergistic catalytic role in denitration catalysis. Therefore, the wet impregnation method is currently mainly used for preparation, specifically adding ammonium metatungstate solution to the metatitanic acid slurry to impregnate the ammonium metatungstate on the surface and pores of the metatitanic acid, and then performing ammonia water neutralization, water washing and filtration, calcination and other processes. In particular, in the process of calcining the metatitanic acid colloid into amorphous titanium dioxide particles, tungsten is evenly and firmly bonded to the titanium dioxide in the form of tungsten trioxide. In this way, titanium dioxide has a synergistic catalytic effect with tungsten in the denitration catalytic process, thereby improving the catalytic activity of the denitration catalyst. However, in this method, ammonium metatungstate cannot be completely impregnated on the surface of metatitanic acid, and a part of it is dissolved in the metatitanic acid slurry and lost to the washing waste liquid during the washing and filtration, especially in the preparation of high tungsten catalyst titanium dioxide (containing WO 3 :9%~10%), the loss of tungsten is even greater. Ammonium metatungstate is expensive, and the loss of tungsten not only causes great economic losses, but also makes the tungsten impurity content in the ammonium sulfate prepared by the subsequent concentrated water washing liquid too high, affecting the quality of the prepared ammonium sulfate.

[0003] In view of this, it is necessary to improve the existing production process of tungsten-containing catalyst titanium dioxide by impregnation method to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry. The preparation process can achieve efficient recycling of tungsten and reduce the energy consumption required for production.

[0005] The process of preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate by using metatitanic acid slurry of the present invention comprises the following steps: (1) Slurrying the washed titanic acid filter cake to prepare titanic acid slurry; (2) stirring and dissolving solid ammonium metatungstate with deionized water to prepare an ammonium metatungstate solution; (3) adding the ammonium metatungstate solution prepared in step (2) into the metatitanic acid slurry to carry out an impregnation reaction under stirring, so that the ammonium metatungstate is impregnated into the surface and pores of the metatitanic acid particles; (4) After the impregnation reaction is completed, the tungsten-containing metatitanic acid slurry obtained in step (3) is subjected to plate-and-frame pressing filtration, and then washed with deionized water for the first time to obtain a plate-and-frame pressing filtrate and a first washing liquid. The obtained plate-and-frame pressing filtrate and the first washing liquid are used for slurrying the metatitanic acid filter cake in step (1), and then ammonia water is pumped into the plate-and-frame for circulating neutralization. Finally, the neutralized filter cake is washed with deionized water for the second time to obtain washing liquid wastewater; (5) The filter cake after washing in step (4) is placed in a rotary kiln for low-temperature calcination to prepare a tungsten-containing catalyst titanium dioxide powder, and the washing liquid wastewater obtained in step (4) is post-treated to prepare high-purity ammonium sulfate.

[0006] in: The equivalent TiO in the titanate slurry described in step (1) 2 The content is 280~320g / L, H 2 SO 4 The content is 18-22g / L.

[0007] The equivalent WO in the ammonium metatungstate solution prepared in step (2) is 3 The content is 150-200g / L.

[0008] In step (3), the immersion reaction time is 1 to 1.5 hours, the immersion temperature is 20 to 40° C., and the stirring speed is 100 to 200 r / min.

[0009] The filtration accuracy of the plate and frame press filtration in step (4) is 0.1µm to 0.3µm, and the pressure of the plate and frame press filtration is 0.3 to 0.5MPa.

[0010] The filter cake obtained by plate and frame pressing and filtration in step (4) is tungsten-containing metatitanic acid, and the filtrate contains tungsten-containing metatitanic acid that has been filtered through, ammonium metatungstate that has not been impregnated into the metatitanic acid, and sulfuric acid, wherein the concentration of tungsten-containing metatitanic acid in the filtrate is 3-5 g / L, the concentration of ammonium metatungstate is 5-10 g / L, and the concentration of sulfuric acid is 12-16 g / L. The first washing with deionized water is 0.5-1.0 ton of deionized water per ton of tungsten-containing catalyst titanium dioxide produced.

[0011] In step (4), the tungsten-containing metatitanic acid slurry is subjected to plate and frame pressing and filtration. For every ton of tungsten-containing catalyst titanium dioxide produced, 2.1 to 2.5 tons of a mixture of plate and frame pressing filtrate and the first water washing liquid are generated. The mixture is relatively large in amount and contains a large amount of metatitanic acid, tungsten and sulfuric acid. The mixture is reused as water for slurrying the metatitanic acid filter cake in step (1).

[0012] In step (4), the plate frame is not depressurized after the squeezing and filtration, and the filter cake does not need to be re-slurried. Instead, ammonia water of a certain concentration is directly pumped into the plate frame for circulating neutralization.

[0013] In step (4), while the plate frame maintains pressure, an excess amount of ammonia water is pumped in to neutralize the sulfuric acid contained in the filter cake, and the pressure is continued to be maintained to wash the neutralized filter cake for a second time to obtain a washing liquid wastewater. The washing liquid wastewater consists of a neutralization product obtained by neutralization and a waste liquid obtained by washing the neutralized filter cake for the second time. The mass ratio of the neutralization product to the waste liquid obtained by washing the neutralized filter cake for the second time is 1:5 to 5.5.

[0014] In step (4), during the production of tungsten-containing catalyst titanium dioxide, excess ammonia water is pumped in while the plate frame maintains pressure to neutralize sulfuric acid in metatitanic acid to generate ammonium sulfate; the reaction equation is as follows: 2NH 3 ·H 2 O+H 2 SO 4 =(NH4) 2 SO 4 +2H 2 O.

[0015] In step (4), when the ammonia water is pumped into the plate frame for circulating neutralization, 13 to 16 kg of ammonia water with a mass concentration of 15% is required to produce 1 ton of tungsten-containing catalyst titanium dioxide.

[0016] Step (4) The neutralized filter cake is washed for the second time with deionized water. 2 to 2.5 tons of deionized water are required to produce 1 ton of tungsten-containing catalyst titanium dioxide to remove ammonium sulfate in the filter cake.

[0017] During the low-temperature calcination in step (5), the temperature of the first ring of the rotary kiln is 130-180°C, the temperature of the second ring is 250-350°C, and the temperature of the third ring is 450-550°C. It takes 6-6.5 hours from the time the washed filter cake enters the rotary kiln to the time the calcination is completed. The feeding method of the washed filter cake in the rotary kiln is continuous feeding.

[0018] The WO in the tungsten-containing catalyst titanium dioxide prepared in step (5) 3 The content accounts for 4.5-10% of the total weight, that is, the production of 1000Kg of tungsten-containing catalyst contains WO 3 The amount is 45~100Kg.

[0019] The post-treatment in step (5) is to evaporate and concentrate the water washing wastewater obtained in step (4), and the concentration of 1m 3The ammonium sulfate solution requires 500 kg of saturated steam with a pressure of 4 kg, which is then pumped into a crystallization tank. When the temperature reaches 30-40°C, it is centrifuged. The ammonium sulfate crystals after centrifugation are dried on a fluidized bed at a drying temperature of 110-120°C for 2-3 hours to obtain finished ammonium sulfate products.

[0020] The ammonium sulfate prepared in step (5) can be directly packaged and sold to compound fertilizer production enterprises.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The process of preparing tungsten-containing catalyst titanium dioxide powder and co-producing high-purity ammonium sulfate using metatitanic acid slurry as described in the present invention uses the plate and frame press filtrate wastewater generated in the production of tungsten-containing catalyst titanium dioxide powder as the slurry for metatitanic acid, which solves the problem of treating tungsten-containing wastewater and saves the amount of deionized water used in slurrying metatitanic acid.

[0022] (2) In the process of preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using titanic acid slurry described in the present invention, neutralization with ammonia water is carried out in a plate frame without reacting in a salt treatment tank, so that the tungsten-containing filtrate does not contain ammonium sulfate generated after the neutralization reaction, and the filtrate can be reused. At the same time, the ammonium sulfate-containing neutralization solution and washing liquid do not contain tungsten-containing titanic acid particles and soluble ammonium metatungstate, thereby ensuring the product quality of the produced ammonium sulfate.

[0023] (3) The process of preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry described in the present invention meets the 100% yield of tungsten, realizes the comprehensive utilization of energy, and greatly reduces the energy consumption required for production; the plate and frame filter press can be used to continuously perform filtration, neutralization, and water washing. After filtration, the filter cake does not need to be re-slurried, realizing continuous operation and a high degree of automation, achieving increased production capacity and reducing the number of equipment, thereby significantly reducing production costs.

[0024] (4) In the process of preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry of the present invention, most of the sulfuric acid is in the filtrate obtained by plate and frame pressing filtration during the early filtration, thereby saving the amount of ammonia water used in neutralization. Since the sulfuric acid content in the filter cake is reduced and the amount of ammonium sulfate produced by neutralization is small, the amount of water used in water washing is reduced, saving the amount of deionized water used in water washing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention discloses a process flow chart for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry. DETAILED DESCRIPTION

[0026] The present invention is further described below with reference to the embodiments.

[0027] Example 1 The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry described in Example 1 is composed of the following steps: (1) Slurrying the washed titanic acid filter cake to prepare titanic acid slurry; (2) stirring and dissolving solid ammonium metatungstate with deionized water to prepare an ammonium metatungstate solution; (3) adding the ammonium metatungstate solution prepared in step (2) into the metatitanic acid slurry to carry out an impregnation reaction under stirring, so that the ammonium metatungstate is impregnated into the surface and pores of the metatitanic acid particles; (4) After the impregnation reaction is completed, the tungsten-containing metatitanic acid slurry obtained in step (3) is subjected to plate-and-frame pressing filtration, and then washed with deionized water for the first time to obtain a plate-and-frame pressing filtrate and a first washing liquid. The obtained plate-and-frame pressing filtrate and the first washing liquid are used for slurrying the metatitanic acid filter cake in step (1), and then ammonia water is pumped into the plate-and-frame for circulating neutralization. Finally, the neutralized filter cake is washed with deionized water for the second time to obtain washing liquid wastewater; (5) The filter cake after washing in step (4) is placed in a rotary kiln for low-temperature calcination to prepare a tungsten-containing catalyst titanium dioxide powder, and the washing liquid wastewater obtained in step (4) is post-treated to prepare high-purity ammonium sulfate.

[0028] in: The equivalent TiO in the titanate slurry described in step (1) 2 The content is 300g / L, H 2 SO 4 The content is 20g / L.

[0029] The equivalent WO in the ammonium metatungstate solution prepared in step (2) is 3 The content is 180g / L.

[0030] In step (3), the immersion reaction time is 1.2 h, the immersion temperature is 30° C., and the stirring speed is 120 r / min.

[0031] The filtration accuracy of the plate and frame press filtration in step (4) is 0.2µm, and the pressure of the plate and frame press filtration is 0.4MPa.

[0032] The filter cake obtained by plate and frame pressing and filtration in step (4) is tungsten-containing metatitanic acid, and the filtrate contains tungsten-containing metatitanic acid that has been filtered through, ammonium metatungstate that has not been impregnated into the metatitanic acid, and sulfuric acid. The concentration of tungsten-containing metatitanic acid in the filtrate is 4 g / L, the concentration of ammonium metatungstate is 8 g / L, and the concentration of sulfuric acid is 13 g / L. The first washing with deionized water is 0.6 tons of deionized water per ton of tungsten-containing catalyst titanium dioxide produced.

[0033] In step (4), the tungsten-containing metatitanic acid slurry is subjected to plate and frame pressing and filtration. For every ton of tungsten-containing catalyst titanium dioxide produced, 2.2 tons of a mixture of plate and frame pressing filtrate and the first water washing liquid are generated. The mixture is relatively large in amount and contains a large amount of metatitanic acid, tungsten and sulfuric acid. The mixture is reused as water for slurrying the metatitanic acid filter cake in step (1).

[0034] In step (4), the plate frame is not depressurized after the squeeze filtration, and the filter cake does not need to be re-slurried. Ammonia water of a certain concentration is directly pumped into the plate frame for circulating neutralization.

[0035] In step (4), while the plate frame maintains pressure, an excess amount of ammonia water is pumped in to neutralize the sulfuric acid contained in the filter cake, and the pressure is continued to be maintained to wash the neutralized filter cake for a second time to obtain a washing liquid wastewater. The washing liquid wastewater consists of a neutralization product obtained by neutralization and a waste liquid obtained by washing the neutralized filter cake for the second time, wherein the mass ratio of the neutralization product to the waste liquid obtained by washing the neutralized filter cake for the second time is 1:5.

[0036] In step (4), during the production of tungsten-containing catalyst titanium dioxide, excess ammonia water is pumped in while the plate frame maintains pressure to neutralize sulfuric acid in metatitanic acid to generate ammonium sulfate; the reaction equation is as follows: 2NH 3 ·H 2 O+H 2 SO 4 =(NH4) 2 SO 4 +2H 2 O.

[0037] In step (4), when the ammonia water is pumped into the plate frame for circulation and neutralization, 14 kg of ammonia water with a mass concentration of 15% is required to produce 1 ton of tungsten-containing catalyst titanium dioxide.

[0038] Step (4) The neutralized filter cake is washed for the second time with deionized water. Two tons of deionized water are required for producing one ton of tungsten-containing catalyst titanium dioxide to remove ammonium sulfate from the filter cake.

[0039] During the low-temperature calcination in step (5), the temperature of the first ring of the rotary kiln is 150°C, the temperature of the second ring is 300°C, and the temperature of the third ring is 500°C. It takes 6 hours from the time the washed filter cake enters the rotary kiln to the time the calcination is completed. The feeding method of the washed filter cake in the rotary kiln is continuous feeding.

[0040] The WO in the tungsten-containing catalyst titanium dioxide prepared in step (5) 3 The content accounts for 5.2% of the total weight, that is, 1000 kg of tungsten-containing catalyst contains WO 3 The amount is 52Kg.

[0041] The post-treatment in step (5) is to evaporate and concentrate the water washing wastewater obtained in step (4), and the concentration of 1m 3 The ammonium sulfate solution requires 500 kg of saturated steam at a pressure of 4 kg, which is then pumped into a crystallization tank. When the temperature reaches 30°C, it is centrifuged. The ammonium sulfate crystals after centrifugation are dried on a fluidized bed at a drying temperature of 110°C and a drying time of 3.0 hours to obtain a finished ammonium sulfate product.

[0042] The test results of the high-purity ammonium sulfate prepared in step (5) are as follows: nitrogen content (on a dry basis): 21.30%, moisture: 0.07%, free acid (H 2 SO 4 ): Not determined, TiO 2 : 0.0028%, water-insoluble matter content: 0.008%, tungsten (W) content: not measured, iron (Fe) content: 0.003%.

[0043] Example 2 The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry described in Example 2 is composed of the following steps: (1) Slurrying the washed titanic acid filter cake to prepare titanic acid slurry; (2) stirring and dissolving solid ammonium metatungstate with deionized water to prepare an ammonium metatungstate solution; (3) adding the ammonium metatungstate solution prepared in step (2) into the metatitanic acid slurry to carry out an impregnation reaction under stirring, so that the ammonium metatungstate is impregnated into the surface and pores of the metatitanic acid particles; (4) After the impregnation reaction is completed, the tungsten-containing metatitanic acid slurry obtained in step (3) is subjected to plate-and-frame pressing filtration, and then washed with deionized water for the first time to obtain a plate-and-frame pressing filtrate and a first washing liquid. The obtained plate-and-frame pressing filtrate and the first washing liquid are used for slurrying the metatitanic acid filter cake in step (1), and then ammonia water is pumped into the plate-and-frame for circulating neutralization. Finally, the neutralized filter cake is washed with deionized water for the second time to obtain washing liquid wastewater; (5) The filter cake after washing in step (4) is placed in a rotary kiln for low-temperature calcination to prepare a tungsten-containing catalyst titanium dioxide powder, and the washing liquid wastewater obtained in step (4) is post-treated to prepare high-purity ammonium sulfate.

[0044] in: The equivalent TiO in the titanate slurry described in step (1) 2 The content is 310g / L, H 2 SO 4 The content is 19g / L.

[0045] The equivalent WO in the ammonium metatungstate solution prepared in step (2) is 3The content is 180g / L.

[0046] In step (3), the immersion reaction time is 1.2 h, the immersion temperature is 30° C., and the stirring speed is 150 r / min.

[0047] The filtration accuracy of the plate and frame press filtration in step (4) is 0.2µm, and the pressure of the plate and frame press filtration is 0.4MPa.

[0048] The filter cake obtained by plate and frame pressing and filtration in step (4) is tungsten-containing titanic acid, and the filtrate contains tungsten-containing titanic acid that has been filtered through, ammonium metatungstate that has not been impregnated into the titanic acid, and sulfuric acid. The concentration of tungsten-containing titanic acid in the filtrate is 4.2 g / L, the concentration of ammonium metatungstate is 8.5 g / L, and the concentration of sulfuric acid is 12 g / L. The first washing with deionized water is 0.8 tons of deionized water per ton of tungsten-containing catalyst titanium dioxide produced.

[0049] In step (4), the tungsten-containing metatitanic acid slurry is subjected to plate and frame pressing and filtration. For every ton of tungsten-containing catalyst titanium dioxide produced, 2.1 tons of a mixture of plate and frame pressing filtrate and the first water washing liquid are generated. The mixture is relatively large in amount and contains a large amount of metatitanic acid, tungsten and sulfuric acid. The mixture is reused as water for slurrying the metatitanic acid filter cake in step (1).

[0050] In step (4), the plate frame is not depressurized after the squeeze filtration, and the filter cake does not need to be re-slurried. Ammonia water of a certain concentration is directly pumped into the plate frame for circulating neutralization.

[0051] In step (4), while the plate frame maintains pressure, an excess amount of ammonia water is pumped in to neutralize the sulfuric acid contained in the filter cake, and the pressure is continued to be maintained to wash the neutralized filter cake for a second time to obtain a washing liquid wastewater. The washing liquid wastewater consists of a neutralization product obtained by neutralization and a waste liquid obtained by washing the neutralized filter cake for the second time. The mass ratio of the neutralization product to the waste liquid obtained by washing the neutralized filter cake for the second time is 1:5.5.

[0052] In step (4), during the production of tungsten-containing catalyst titanium dioxide, excess ammonia water is pumped in while the plate frame maintains pressure to neutralize sulfuric acid in metatitanic acid to generate ammonium sulfate; the reaction equation is as follows: 2NH 3 ·H 2 O+H 2 SO 4 =(NH4) 2 SO 4 +2H 2 O.

[0053] In step (4), when the ammonia water is pumped into the plate frame for circulation and neutralization, 13.8 kg of ammonia water with a mass concentration of 15% is required to produce 1 ton of tungsten-containing catalyst titanium dioxide.

[0054] Step (4) The neutralized filter cake is washed for the second time with deionized water. Two tons of deionized water are required for producing one ton of tungsten-containing catalyst titanium dioxide to remove ammonium sulfate from the filter cake.

[0055] During the low-temperature calcination in step (5), the temperature of the first ring of the rotary kiln is 150°C, the temperature of the second ring is 300°C, and the temperature of the third ring is 500°C. It takes 6 hours from the time the washed filter cake enters the rotary kiln to the time the calcination is completed. The feeding method of the washed filter cake in the rotary kiln is continuous feeding.

[0056] The WO in the tungsten-containing catalyst titanium dioxide prepared in step (5) 3 The content accounts for 7.5% of the total weight, that is, 1000 kg of tungsten-containing catalyst contains WO 3 The amount is 75Kg.

[0057] When the water washing wastewater is evaporated and concentrated in step (5), each concentration of 1m 3 The ammonium sulfate solution requires 500 kg of saturated steam at a pressure of 4 kg, which is then pumped into a crystallization tank. When the temperature reaches 40°C, it is centrifuged. The ammonium sulfate crystals after centrifugation are dried on a fluidized bed at a drying temperature of 120°C and a drying time of 2.0 hours to obtain finished ammonium sulfate products.

[0058] The test results of the high-purity ammonium sulfate prepared in step (5) are as follows: nitrogen content (on a dry basis): 21.10%, moisture: 0.07%, free acid (H 2 SO 4 ): Not determined, TiO 2 : 0.0028%, water-insoluble matter content: 0.007%, tungsten (W) content: not measured, iron (Fe) content: 0.003%.

[0059] Example 3 The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry described in Example 3 is composed of the following steps: (1) Slurrying the washed titanic acid filter cake to prepare titanic acid slurry; (2) stirring and dissolving solid ammonium metatungstate with deionized water to prepare an ammonium metatungstate solution; (3) adding the ammonium metatungstate solution prepared in step (2) into the metatitanic acid slurry to carry out an impregnation reaction under stirring, so that the ammonium metatungstate is impregnated into the surface and pores of the metatitanic acid particles; (4) After the impregnation reaction is completed, the tungsten-containing metatitanic acid slurry obtained in step (3) is subjected to plate-and-frame pressing filtration, and then washed with deionized water for the first time to obtain a plate-and-frame pressing filtrate and a first washing liquid. The obtained plate-and-frame pressing filtrate and the first washing liquid are used for slurrying the metatitanic acid filter cake in step (1), and then ammonia water is pumped into the plate-and-frame for circulating neutralization. Finally, the neutralized filter cake is washed with deionized water for the second time to obtain washing liquid wastewater; (5) The filter cake after washing in step (4) is placed in a rotary kiln for low-temperature calcination to prepare a tungsten-containing catalyst titanium dioxide powder, and the washing liquid wastewater obtained in step (4) is post-treated to prepare high-purity ammonium sulfate.

[0060] in: The equivalent TiO in the titanate slurry described in step (1) 2 The content is 290g / L, H 2 SO 4 The content is 19g / L.

[0061] The equivalent WO in the ammonium metatungstate solution prepared in step (2) is 3 The content is 180g / L.

[0062] In step (3), the immersion reaction time is 1.5 h, the immersion temperature is 30° C., and the stirring speed is 180 r / min.

[0063] The filtration accuracy of the plate and frame press filtration in step (4) is 0.2µm, and the pressure of the plate and frame press filtration is 0.4MPa.

[0064] The filter cake obtained by plate and frame pressing and filtration in step (4) is tungsten-containing metatitanic acid, and the filtrate contains tungsten-containing metatitanic acid that has been filtered through and ammonium metatungstate that has not been impregnated into the metatitanic acid, as well as sulfuric acid. The concentration of tungsten-containing metatitanic acid in the filtrate is 4 g / L, the concentration of ammonium metatungstate is 10 g / L, and the concentration of sulfuric acid is 13 g / L. The first washing with deionized water is 0.6 tons of deionized water per ton of tungsten-containing catalyst titanium dioxide produced.

[0065] In step (4), the tungsten-containing metatitanic acid slurry is subjected to plate and frame pressing and filtration. For every ton of tungsten-containing catalyst titanium dioxide produced, 2.5 tons of a mixture of plate and frame pressing filtrate and the first water washing liquid are generated. The mixture is relatively large in amount and contains a large amount of metatitanic acid, tungsten and sulfuric acid. The mixture is reused as water for slurrying the metatitanic acid filter cake in step (1).

[0066] In step (4), the plate frame is not depressurized after the squeeze filtration, and the filter cake does not need to be re-slurried. Ammonia water of a certain concentration is directly pumped into the plate frame for circulating neutralization.

[0067] In step (4), while the plate frame maintains pressure, an excess amount of ammonia water is pumped in to neutralize the sulfuric acid contained in the filter cake, and the pressure is continued to be maintained to wash the neutralized filter cake for a second time to obtain a washing liquid wastewater. The washing liquid wastewater consists of a neutralization product obtained by neutralization and a waste liquid obtained by washing the neutralized filter cake for the second time. The mass ratio of the neutralization product to the waste liquid obtained by washing the neutralized filter cake for the second time is 1:5.2.

[0068] In step (4), during the production of tungsten-containing catalyst titanium dioxide, excess ammonia water is pumped in while the plate frame maintains pressure to neutralize sulfuric acid in metatitanic acid to generate ammonium sulfate; the reaction equation is as follows: 2NH 3 ·H 2 O+H 2 SO 4 =(NH4) 2 SO 4 +2H 2 O.

[0069] In step (4), when the ammonia water is pumped into the plate frame for circulating neutralization, 14.2 kg of ammonia water with a mass concentration of 15% is required to produce 1 ton of tungsten-containing catalyst titanium dioxide.

[0070] Step (4) The neutralized filter cake is washed for the second time with deionized water. Two tons of deionized water are required for producing one ton of tungsten-containing catalyst titanium dioxide to remove ammonium sulfate from the filter cake.

[0071] During the low-temperature calcination in step (5), the temperature of the first ring of the rotary kiln is 150°C, the temperature of the second ring is 300°C, and the temperature of the third ring is 520°C. It takes 6.5 hours from the time the washed filter cake enters the rotary kiln to the time the calcination is completed.

[0072] The WO in the tungsten-containing catalyst titanium dioxide prepared in step (5) 3 The content accounts for 10% of the total weight, that is, the production of 1000Kg of tungsten-containing catalyst contains WO 3 The amount is 100Kg.

[0073] The post-treatment in step (5) is to evaporate and concentrate the water washing wastewater obtained in step (4), and the concentration of 1m 3 The ammonium sulfate solution requires 500 kg of saturated steam at a pressure of 4 kg, which is then pumped into a crystallization tank. When the temperature reaches 35°C, it is centrifuged. The ammonium sulfate crystals after centrifugation are dried on a fluidized bed at a drying temperature of 115°C and a drying time of 2.5 hours to obtain finished ammonium sulfate product.

[0074] The test results of the high-purity ammonium sulfate prepared in step (5) are as follows: nitrogen content (on a dry basis): 21.30%, moisture: 0.06%, free acid (H 2 SO4 ): Not determined, TiO 2 : 0.0020%, water-insoluble matter content: 0.008%, tungsten (W) content: not measured, iron (Fe) content: 0.002%.

[0075] Comparative Example 1 The process for preparing tungsten-containing catalyst titanium dioxide and co-producing ammonium sulfate using metatitanic acid slurry in Comparative Example 1 is composed of the following steps: (1) Slurrying the washed titanic acid filter cake to prepare titanic acid slurry; (2) stirring and dissolving solid ammonium metatungstate with deionized water to prepare an ammonium metatungstate solution; (3) adding the ammonium metatungstate solution prepared in step (2) into the metatitanic acid slurry to carry out an impregnation reaction under stirring, so that the ammonium metatungstate is impregnated into the surface and pores of the metatitanic acid particles; (4) adding excess ammonia water to the tungsten-containing metatitanic acid slurry prepared in step (3), adjusting the pH of the reaction system to 11.0, and then filtering and washing the filter cake with water to obtain a washing liquid wastewater and a filter cake; (5) The filter cake after washing in step (4) is placed in a rotary kiln for low-temperature calcination to prepare a tungsten-containing catalyst titanium dioxide, and the washing liquid wastewater obtained in step (4) is post-treated to prepare ammonium sulfate.

[0076] in: The equivalent TiO in the titanate slurry described in step (1) 2 The content is 300g / L, H 2 SO 4 The content is 20g / L.

[0077] The equivalent WO in the ammonium metatungstate solution prepared in step (2) is 3 The content is 180g / L.

[0078] In step (3), the immersion reaction time is 1.2 h, the immersion temperature is 30° C., and the stirring speed is 120 r / min.

[0079] The filtration accuracy of the plate and frame press filtration in step (4) is 0.2µm, and the pressure of the plate and frame press filtration is 0.4MPa.

[0080] The step (4) is then filtered and the filter cake is washed with water to obtain a filtrate and a filter cake. The filter cake is tungsten-containing metatitanic acid. The filter cake is washed with water to obtain a washing liquid wastewater, wherein the mass ratio of the filtrate obtained by filtration to the washing liquid wastewater obtained by washing the filter cake is 1:3.

[0081] In step (4), 5 tons of deionized water are required for producing 1 ton of tungsten-containing catalyst titanium dioxide to remove ammonium sulfate in the filter cake, excess ammonia water and ammonium metatungstate that has not been impregnated into the metatitanic acid.

[0082] Step (5) The filter cake obtained in step (4) is sent to a rotary kiln low-temperature calcination system for calcination. The temperature of the first ring of the rotary kiln is 180°C, the temperature of the second ring is 350°C, and the temperature of the third ring is 550°C. It takes 6 hours from the time the metatitanic acid enters the rotary kiln to the completion of calcination.

[0083] The WO in the tungsten-containing catalyst titanium dioxide prepared in step (5) 3 The content accounts for 5.2% of the total weight, that is, 1000 kg of tungsten-containing catalyst contains WO 3 The amount is 52Kg.

[0084] The post-treatment in step (5) is to evaporate and concentrate the water washing wastewater obtained in step (4), and the concentration of 1m 3 The ammonium sulfate solution requires 500 kg of saturated steam at a pressure of 4 kg, which is then pumped into a crystallization tank. When the temperature reaches 30°C, it is centrifuged. The ammonium sulfate crystals after centrifugation are dried on a fluidized bed at a drying temperature of 110°C and a drying time of 3.0 hours to obtain a finished ammonium sulfate product.

[0085] The test results of the ammonium sulfate prepared in step (5) are as follows: nitrogen content (on a dry basis): 20.89%, moisture: 0.07%, free acid (H 2 SO 4 ): Not determined, TiO 2 : 0.030%, water-insoluble matter content: 0.010%, tungsten (W) content: 0.05%, iron (Fe) content: 0.009%.

[0086] Through the above experiments, it can be seen that the ammonium sulfate prepared in Examples 1-3 does not contain impurity tungsten, indicating that tungsten has achieved 100% recovery. Compared with Comparative Example 1, Example 1 has a high tungsten content and titanium content in the prepared ammonium sulfate, and many impurities when the calcination temperature of the rotary kiln is increased, resulting in the loss and waste of tungsten, and the amount of deionized water used in water washing is significantly greater than that of Example 1.

Claims

1. A process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry, characterized in that: It consists of the following steps: (1) Slurrying the washed titanic acid filter cake to prepare titanic acid slurry; (2) stirring and dissolving solid ammonium metatungstate with deionized water to prepare an ammonium metatungstate solution; (3) adding the ammonium metatungstate solution prepared in step (2) into the metatitanic acid slurry to carry out an impregnation reaction under stirring, so that the ammonium metatungstate is impregnated into the surface and pores of the metatitanic acid particles; (4) After the impregnation reaction is completed, the tungsten-containing metatitanic acid slurry obtained in step (3) is subjected to plate-and-frame pressing filtration, and then washed with deionized water for the first time to obtain a plate-and-frame pressing filtrate and a first washing liquid. The obtained plate-and-frame pressing filtrate and the first washing liquid are used for slurrying the metatitanic acid filter cake in step (1), and then ammonia water is pumped into the plate-and-frame for circulating neutralization. Finally, the neutralized filter cake is washed with deionized water for the second time to obtain washing liquid wastewater; (5) The filter cake after washing in step (4) is placed in a rotary kiln for low-temperature calcination to prepare a tungsten-containing catalyst titanium dioxide powder, and the washing liquid wastewater obtained in step (4) is post-treated to prepare high-purity ammonium sulfate.

2. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: The equivalent TiO2 content in the titanate slurry described in step (1) is 280-320 g / L, and the H2SO4 content is 18-22 g / L.

3. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: The equivalent WO3 content in the ammonium metatungstate solution prepared in step (2) is 150-200 g / L.

4. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: In step (3), the immersion reaction time is 1 to 1.5 hours, the immersion temperature is 20 to 40° C., and the stirring speed is 100 to 200 r / min.

5. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: The filtration accuracy of the plate and frame press filtration in step (4) is 0.1µm to 0.3µm, and the pressure of the plate and frame press filtration is 0.3 to 0.5MPa; The filter cake obtained by plate and frame pressing and filtration in step (4) is tungsten-containing metatitanic acid, and the filtrate contains tungsten-containing metatitanic acid that has been filtered through, ammonium metatungstate that has not been impregnated into the metatitanic acid, and sulfuric acid, wherein the concentration of tungsten-containing metatitanic acid in the filtrate is 3-5 g / L, the concentration of ammonium metatungstate is 5-10 g / L, and the concentration of sulfuric acid is 12-16 g / L. The first washing with deionized water is 0.5-1.0 ton of deionized water per ton of tungsten-containing catalyst titanium dioxide produced.

6. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: In step (4), the tungsten-containing metatitanic acid slurry is subjected to plate-frame pressing and filtration, and a mixture of 2.1 to 2.5 tons of plate-frame pressing filtrate and the first water washing liquid is produced for every ton of tungsten-containing catalyst titanium dioxide, which is reused as water for slurrying the metatitanic acid filter cake in step (1); The water washing wastewater in step (4) consists of two parts: the neutralization product liquid obtained by neutralization and the waste liquid obtained by washing the neutralized filter cake for the second time, wherein the mass ratio of the neutralization product liquid to the waste liquid obtained by washing the neutralized filter cake for the second time is 1:5 to 5.

5.

7. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: In step (4), when the ammonia water is pumped into the plate frame for circulation and neutralization, 13-16 kg of ammonia water with a mass concentration of 15% is required to produce 1 ton of tungsten-containing catalyst titanium dioxide; Step (4) The neutralized filter cake is washed for the second time with deionized water. 2 to 2.5 tons of deionized water are required to produce 1 ton of tungsten-containing catalyst titanium dioxide to remove ammonium sulfate in the filter cake.

8. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: During the low-temperature calcination in step (5), the temperature of the first ring of the rotary kiln is 130-180°C, the temperature of the second ring is 250-350°C, and the temperature of the third ring is 450-550°C. It takes 6-6.5 hours from the time the washed filter cake enters the rotary kiln to the time the calcination is completed. The feeding method of the washed filter cake in the rotary kiln is continuous feeding.

9. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1 is characterized in that: The WO3 content in the tungsten-containing catalyst titanium dioxide prepared in step (5) accounts for 4.5-10% of the total weight, that is, the amount of WO3 contained in 1000 kg of tungsten-containing catalyst is 45-100 kg.

10. The process for preparing tungsten-containing catalyst titanium dioxide and co-producing high-purity ammonium sulfate using metatitanic acid slurry according to claim 1, characterized in that: The post-treatment in step (5) is to evaporate and concentrate the water washing wastewater obtained in step (4), and the concentration of 1m 3 The ammonium sulfate solution requires 500 kg of saturated steam with a pressure of 4 kg, which is then pumped into a crystallization tank. When the temperature reaches 30-40°C, it is centrifuged. The ammonium sulfate crystals after centrifugation are dried on a fluidized bed at a drying temperature of 110-120°C for 2-3 hours to obtain finished ammonium sulfate products.

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