Lateral flow causticizing system for washing liquor

Abstract

The utility model discloses a washing liquor side flow causticizing system in the technical field of aluminum oxide production, which comprises a first causticizing reaction tank and is characterized in that the first causticizing reaction tank is connected with a centrifugal machine, the centrifugal machine is connected with a filter cake tank and a filtrate tank, the filter cake tank is connected with a first-stage preheater, the first-stage preheater is connected with a second-stage preheater, and the second-stage preheater is connected with a third-stage preheater. The secondary preheater is connected with a new steam heater, the new steam heater is connected with a secondary causticizing first-section reaction tank, the secondary causticizing first-section reaction tank is connected with a secondary causticizing second-section reaction tank, the secondary causticizing second-section reaction tank is fixedly connected with an under-pressure separation tank, the under-pressure separation tank is connected with a secondary flash evaporator, the secondary flash evaporator is connected with a primary flash evaporator, and the primary flash evaporator is connected with a secondary flash evaporator. The first-stage preheater is connected with a second steam condensate water tank, and the second steam condensate water tank is connected with the first steam condensate water tank. The system can effectively reduce the content of carbon and alkali in the washing liquid.

Description

Technical Field

[0001] The utility model belongs to the technical field of aluminum oxide production, and particularly relates to a washing liquid side-flow causticizing system. Background Art

[0002] With the continuous exploitation of bauxite resources, the grade of the originally abundant low-carbon bauxite has gradually declined, forcing alumina manufacturers to switch to using bauxite with relatively high grade but high carbon content. Although this shift has alleviated the tension in ore supply to a certain extent, the use of high-carbon bauxite has led to a significant increase in the concentration of sodium carbonate in the alumina production system, causing the carbon-alkali ratio of the entire production system to climb to an astonishing 12% to 16%. This change brings the following problems: 1. Due to the increase in sodium carbonate concentration, the solubility of salt in the production system changes, making the salt discharge process more complicated and difficult, affecting the stable operation of the system. 2. High concentrations of sodium carbonate significantly increase heat consumption in the production process, especially in process links such as evaporation and concentration, which requires more steam to maintain the production temperature, thereby increasing energy consumption costs. 3. The increase in sodium carbonate concentration may also interfere with the decomposition process of alumina, causing the decomposition rate to decrease, reducing the output and quality of the product. 4. The combined effect of the above factors leads to a decrease in the operating efficiency of the entire production system, which in turn affects the total output of alumina. 5. Enterprises need to invest more funds in equipment transformation, energy consumption and waste disposal. These additional expenditures will undoubtedly increase the production cost of alumina. Utility Model Content

[0003] The utility model aims to provide a washing liquid side-flow causticizing system to reduce the carbon alkali content in the washing liquid.

[0004] A washing liquid side stream causticizing system in the present scheme comprises a caustic reaction tank, the caustic reaction tank is connected to a centrifuge, the centrifuge is connected to a filter cake tank and a filtrate tank, the filter cake tank is connected to a primary preheater, the primary preheater is connected to a secondary preheater, the secondary preheater is connected to a new steam heater, the new steam heater is connected to a second caustic first stage reaction tank, the second caustic first stage reaction tank is connected to a second caustic second stage reaction tank, the second caustic second stage reaction tank is fixedly connected to a pressurized separation tank, the pressurized separation tank is connected to a secondary flash evaporator, the secondary flash evaporator is connected to the primary flash evaporator, the primary preheater is connected to a second steam condensate water tank, and the second steam condensate water tank is connected to the first steam condensate water tank.

[0005] Furthermore, the caustic reaction tank is connected to a heat exchanger, and the heat exchanger is connected to a centrifuge.

[0006] Furthermore, the heat exchanger is a wide channel heat exchanger for cooling the washing liquid to 70-90°C.

[0007] Furthermore, the reaction tank is connected to the centrifuge via a slurry pump, so that the slurry can be transported to the centrifuge more conveniently.

[0008] Furthermore, the secondary flash evaporator is connected to the secondary preheater. The secondary flash evaporator is used to flash the slurry.

[0009] Furthermore, the primary flash evaporator is connected to the filtrate tank. The primary flash evaporator is used to flash the slurry.

[0010] Furthermore, the first steam condensate tank is connected to the primary preheater and the secondary preheater.

[0011] Furthermore, the first steam condensate tank is a tubular heater, which is used to heat the mixed liquid in the filter cake tank at a heating temperature of 90-150°C.

[0012] Beneficial effects:

[0013] The utility model uses a heat exchanger to cool down, and processes the washing liquid through a caustic reaction tank, and performs flash evaporation and sedimentation through subsequent process steps, which can effectively reduce the carbon and alkali content in the washing liquid, enable the production process to effectively discharge salt, solve the problems of dissolving exhaust steam with materials, and increasing heat consumption due to water injection into the dissolution unit, and can also enable the production system to have the ability to use high-carbon ore, expanding the scope of ore use. In the case of using high-carbon bauxite for production, it can improve production efficiency, reduce energy consumption and increase displacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a schematic structural diagram of a washing liquid side stream causticizing system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The following is further described in detail through specific implementation methods:

[0016] The figure marks in the drawings of the specification include: a first caustic reaction tank 1, a centrifuge 2, a heat exchanger 3, a filter cake tank 4, a filtrate tank 5, a primary preheater 6, a secondary preheater 7, a new steam heater 8, a second caustic first stage reaction tank 9, a second caustic second stage reaction tank 10, a pressurized separation tank 11, a secondary flash evaporator 12, a primary flash evaporator 13, a first steam condensate tank 14, and a second steam condensate tank 15.

[0017] The embodiment is basically as shown in the attached Figure 1As shown: a washing liquid side stream causticizing system, comprising a caustic reaction tank 1, a caustic reaction tank 1 is connected to a centrifuge 2 through a slurry pump, a caustic reaction tank 1 is connected to a heat exchanger 3 through a connecting pipe, the heat exchanger 3 and the centrifuge 2 are fixedly connected, the heat exchanger 3 is a wide channel heat exchanger 3, a washing liquid cooling, the washing liquid is cooled to 70-90°C, the centrifuge 2 is connected to a filter cake tank 4 and a filtrate tank 5, the filter cake tank 4 is connected to a primary preheater 6, the primary preheater 6 is connected to a secondary preheater 7, the secondary preheater 7 is connected to a new steam heater 8, the new steam heater 8 is connected to a second caustic first stage reaction tank 9, the second caustic first stage reaction tank 9 is connected to a second caustic second stage reaction tank 10, the second caustic second stage reaction tank 10 is connected to a pressurized separation tank 11. The pressurized separation tank 11 is connected with a secondary flash evaporator 12, which is connected with a secondary preheater 7. The secondary flash evaporator 12 is used for flashing the slurry. The secondary flash evaporator 12 is connected with a primary flash evaporator 13, which is connected with a filtrate tank 5. The primary flash evaporator 13 is used for flashing the slurry. The primary preheater 6 is connected with a second steam condensate tank 15, which is connected with a first steam condensate tank 14, which is connected with the primary preheater 6, which is connected with the first steam condensate tank 14, which is connected with the primary preheater 6, which is connected with the secondary preheater 7. The first steam condensate tank 14 is a tubular heater, which is used for heating the mixed liquid in the filter cake tank 4, and the heating temperature is 90-150°C.

[0018] The specific implementation process is as follows:

[0019] In this embodiment, the wash liquid side stream causticizing system (sodium aluminate solution causticizing system) acts on the primary wash liquid, which is a sodium aluminate solution from the overflow of a settling tank, wherein the main components are caustic soda with a concentration of 50-90 g / L, alumina with a concentration of 55-95 g / L, and sodium carbonate with a concentration of 6-20 g / L. The primary wash liquid is cooled to 75-90° C. by a heat exchanger 3, and a causticizing aid and lime milk are added to a caustic reaction tank 1 to react to generate a hydrocalumite slurry, which is then separated by a centrifuge 2 to obtain a filtrate and a hydrocalumite filter cake, and the hydrocalumite filter cake is mixed with another 250 m 3 / hThe primary washing liquid is mixed and slurried in the filter cake tank 4, and then the slurry is heated to 120-130°C by flash secondary steam and new steam, and then enters the second caustic first stage reaction tank 9, the second caustic second stage reaction tank 10, and finally enters the pressurized separation tank 11. The overflow of the pressurized separation tank 11 is flashed through the secondary flash evaporator 12 and the primary flash evaporator 13, and then goes to the filtrate tank 5. The bottom flow of the pressurized separation tank 11 is the causticized slag solid for sedimentation and secondary washing. The medium in the filtrate tank 5 is the primary washing liquid after decarbonation and alkali removal, and then pumped to the dissolution dilution tank.

[0020] The above is only an embodiment of the utility model, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the utility model, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A wash liquor side stream causticizing system, comprising a causticizing reaction tank, characterized in that: The first reaction tank is connected to a centrifuge, the centrifuge is connected to a filter cake tank and a filtrate tank, the filter cake tank is connected to a first-level preheater, the first-level preheater is connected to a second-level preheater, the second-level preheater is connected to a new steam heater, the new steam heater is connected to a second-stage reaction tank, the second-stage reaction tank is connected to a second-stage reaction tank, the second-stage reaction tank is fixedly connected to a pressurized separation tank, the pressurized separation tank is connected to a second-level flash evaporator, the second-level flash evaporator is connected to the first-level flash evaporator, the first-level preheater is connected to a second steam condensate water tank, and the second steam condensate water tank is connected to the first steam condensate water tank.

2. A wash liquor side stream causticizing system according to claim 1, characterized in that: The caustic reaction tank is connected with a heat exchanger, and the heat exchanger is connected with a centrifuge.

3. A wash liquid side stream causticizing system according to claim 2, characterized in that: The heat exchanger is a wide channel heat exchanger.

4. A wash liquor side stream causticizing system according to claim 3, characterized in that: The harsh reaction tank is connected to the centrifuge through a slurry pump.

5. A wash liquid side stream causticizing system according to any one of claims 1 to 4, characterized in that: The secondary flash evaporator is connected to the secondary preheater.

6. A wash liquor side stream causticizing system according to claim 5, characterized in that: The first-stage flash evaporator is connected to the filtrate tank.

7. A wash liquor side stream causticizing system according to claim 6, characterized in that: The first steam condensate tank is connected to the primary preheater and the secondary preheater.

8. A wash liquor side stream causticizing system according to claim 7, characterized in that: The first steam condensate tank is a tubular heater.

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