CN113262561A

CN113262561A - Fine seed slurry concentration device and method

Info

Publication number: CN113262561A
Application number: CN202110758082.6A
Authority: CN
Inventors: 赵成明; 李志国; 陈玉国; 孙斌
Original assignee: Shenyang Aluminum and Magnesium Engineering and Research Institute Co Ltd
Current assignee: Shenyang Aluminum and Magnesium Engineering and Research Institute Co Ltd
Priority date: 2021-07-05
Filing date: 2021-07-05
Publication date: 2021-08-17
Anticipated expiration: 2041-07-05
Also published as: CN113262561B

Abstract

A fine seed slurry concentration device and a method belong to the technical field of alumina production two-stage decomposition, and the device comprises a hydraulic clarifier, wherein the hydraulic clarifier is connected with a hydraulic clarifier feeding tank through a feeding pump, and the hydraulic clarifier feeding tank is connected with a secondary hydraulic cyclone; the hydraulic clarifier is characterized in that a cyclone for separating slurry is arranged in the hydraulic clarifier, an overflow port of the cyclone is connected with an overflow box, a sand settling nozzle of the cyclone is connected with an underflow box, the overflow box is connected with a mother liquor tank, and the underflow box is connected with a vertical disc filter. The invention cancels a fine seed settling tank in the aluminum hydroxide grading process, simultaneously ensures that the graded aluminum hydroxide slurry meets the feeding solid content requirement of the vertical disc filter, the solid content of the graded mother liquor is not more than 1g/L, reduces the investment and operation cost, and improves the production regulating capacity.

Description

Fine seed slurry concentration device and method

Technical Field

The invention belongs to the technical field of two-stage decomposition in alumina production, and particularly relates to a fine seed slurry concentration device and method.

Background

With the increasing awareness of environmental protection and the demand of energy conservation, the sand-shaped alumina with a plurality of advantages gradually replaces powdery alumina and intermediate alumina and becomes the preferred raw material of an electrolytic aluminum plant. At present, two decomposition processes, namely a one-stage method and a two-stage method, are used for producing alumina at home and abroad. The bauxite adopted by the existing alumina plant in China is mostly hard-soluble diaspore, the decomposition process adopts a one-stage decomposition process, and the product quality hardly meets the index requirement of sandy alumina. The two-stage decomposition process can improve the crystallization process of the aluminum hydroxide, improve the strength and granularity of the product aluminum oxide and is suitable for being used as a technical scheme for producing sandy aluminum oxide.

The most common flow of two-stage decomposition is: the aluminum hydroxide slurry in the decomposition end tank is subjected to primary classification through a primary hydrocyclone, underflow coarse aluminum hydroxide particles serving as finished products enter a flat disc filter and overflow to a secondary hydrocyclone for further classification; and the overflow of the secondary hydrocyclone is concentrated by a settling tank and then filtered by a vertical disc filter or a horizontal belt filter to obtain fine seeds, and the underflow of the hydrocyclone and the residual slurry discharged from the seed precipitation tank are mixed and filtered together to obtain coarse seeds. The fine seeds and the coarse seeds are respectively used as seed crystal particles for decomposing agglomeration sections and growing sections, and the sodium aluminate solution is continuously decomposed to obtain the aluminum hydroxide product.

Generally, the solid content of the overflow of the secondary hydrocyclone containing fine aluminum hydroxide particles is 100-200 g/L, which cannot be directly processed by a vertical disc filter, and the horizontal belt filter occupies a large area and has small capacity, which is not suitable for the fine seed filtering process of a large-scale alumina plant, so the overflow of the secondary hydrocyclone must be sent to a concentration device to generate concentrated slurry with the solid content of more than 200g/L, which is suitable for being sent to the vertical disc filter, and overflow mother liquor with the solid content of less than or equal to 1g/L is obtained. The fine seed settling tank is used as a concentration device in the grading process and is widely applied to two-stage decomposition. As the particles with the diameter of below-45 mu m in the fine seed slurry reach 20-60 percent, the sedimentation speed is low, and meanwhile, in order to obtain clear mother liquor with the solid content of less than or equal to 1g/L, the area required by a fine seed sedimentation tank is still large under the condition of adding a hydrate flocculating agent, a single line 100 million tons of alumina factories are generally required to be provided with not less than 3 sedimentation tanks with the diameter of 40m, and each sedimentation tank is provided with 4 rake motors with the power of 7.5 kW. The large diameter fine seed settling tank takes up large land, high investment, high operating costs, and the equipment is very sensitive to fine seed slurry flow and solids variation, often resulting in production interruptions due to rake system overload trips.

Disclosure of Invention

In order to solve the technical problems, the invention provides a fine seed slurry concentration device and a fine seed slurry concentration method, and aims to eliminate a fine seed settling tank in an aluminum hydroxide classification process, ensure that classified aluminum hydroxide slurry meets the requirement of a vertical disc filter on solid content of fed materials and the solid content of classified mother liquor is not more than 1g/L, reduce investment and operation cost and improve production regulation capacity.

In order to achieve the purpose, the invention adopts the following technical scheme:

a fine seed slurry concentration device comprises a hydraulic clarifier, wherein the hydraulic clarifier is connected with a feed trough of the hydraulic clarifier through a feed pump, and the feed trough of the hydraulic clarifier is connected with a secondary hydrocyclone; the hydraulic clarifier is characterized in that a cyclone for separating slurry is arranged in the hydraulic clarifier, an overflow port of the cyclone is connected with an overflow box, a sand settling nozzle of the cyclone is connected with an underflow box, the overflow box is connected with a mother liquor tank, and the underflow box is connected with a vertical disc filter.

Furthermore, a chassis is arranged in the hydraulic clarifier, a feed inlet is formed in the bottom of the chassis, a plurality of clarification cabins are arranged on the chassis, the feed inlet is communicated with inlets of the plurality of clarification cabins, a feed box connected with the feed inlet is arranged in the clarification cabins, the feed box is communicated with the plurality of cyclones respectively, and overflow ports of the cyclones in each clarification cabin are connected with an overflow box respectively.

A method for concentrating fine seed slurry comprises the steps that overflow of a secondary hydrocyclone automatically flows into a feeding trough of a hydraulic clarifier and is sent into the hydraulic clarifier through a feeding pump, after solid-liquid separation is carried out on the slurry through a plurality of cyclones in the hydraulic clarifier, the overflow with the solid content not more than 1g/L enters an overflow tank and automatically flows into a mother liquid tank through an overflow pipe; the underflow with solid content more than 200g/L enters an underflow box, enters a vertical disc filter through an underflow pipe, and the filtered fine seed filter cake is continuously washed by water to remove oxalate or is directly added into a first-stage decomposition agglomeration tank as fine seeds.

The invention has the following advantages and beneficial effects:

1. by adding the hydraulic clarifier, the original fine seed settling tank and the auxiliary equipment thereof are eliminated, the occupied area is greatly saved, and the capital investment is reduced.

2. By adding the hydraulic clarifier, the problem that the underflow of a secondary cyclone arranged at a high position in the original flow enters a settling tank for concentration and needs to be returned to a vertical disc filter positioned at the high position by an underflow pump, namely the potential energy of slurry is lost, is avoided. Thereby saving electric energy and reducing the operation cost.

3. The fine seed settling tank is eliminated, so that an organic flocculant added into the settling tank for accelerating the settling of fine seed particles is eliminated, and the phenomenon that extra organic carbon enters the flow to pollute products and seed precipitation mother liquor is avoided.

4. The strength of the fine particles growing at low temperature in the decomposition tank is not high, the dendritic branches are easy to grow, the overflow fine seed slurry of the secondary hydrocyclone flows at high speed along the outer wall in the cyclone of the hydraulic clarifier, compared with the free sedimentation in the sedimentation tank, more dendritic crystals are broken into fine seed particles with finer granularity and higher strength after violent impact, the decomposition and agglomeration process is facilitated, and the product quality is improved.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention;

FIG. 2 is a schematic diagram of a hydrodynamic clarifier of the present invention.

In the figure: 1. a hydraulic clarifier feed tank; 2. a feed pump; 3. a hydraulic clarifier; 4. a vertical disc filter; 5. a feed inlet; 6. a feeding box; 7. a cyclone; 8. an overflow tank; 9. an overflow port; 10. an underflow box; 11. and a bottom flow port.

Detailed Description

The invention is further explained below with reference to the figures and the examples.

The invention provides a fine seed slurry concentration device and a method, as shown in figures 1 and 2, the fine seed slurry concentration device comprises a hydraulic clarifier 3, the hydraulic clarifier 3 is connected with a hydraulic clarifier feeding tank 1 through a feeding pump 2, the hydraulic clarifier feeding tank 1 is connected with a secondary hydraulic cyclone, a cyclone 7 for separating slurry is arranged in the hydraulic clarifier 3, the overflow port of the cyclone is connected with an overflow tank 8, the sand settling nozzle of the cyclone is connected with an underflow tank 10, the overflow tank 10 is connected with a mother liquor tank, and the underflow tank 10 is connected with a vertical disc filter 4. A plurality of clarification cabins which are connected in parallel are arranged in the hydraulic clarifier 3, and a plurality of rotational flow members 7 which are connected in parallel are arranged in each clarification cabin. The hydraulic clarifier is characterized in that a base plate is arranged in the hydraulic clarifier, a feed port 5 is arranged at the bottom of the base plate, the feed port 5 is connected with inlets of all clarification cabins in parallel, a feed box 6 connected with the feed port is arranged in each clarification cabin, and the feed box 6 is connected with all swirlers 7. The overflow solid content of the hydraulic clarifier is not more than 1 g/L; the solid content of the underflow of the hydraulic clarifier is more than 200 g/L. After solid-liquid separation of the cyclone in the hydraulic clarifier, the overflow with solid content not more than 1g/L enters the overflow tank and automatically flows into the mother liquid tank through the overflow pipe, the bottom flow with solid content more than 200g/L enters the bottom flow tank and enters the vertical disc filter through the bottom flow pipe.

The invention provides a method for concentrating fine seed slurry, wherein overflow of a secondary hydrocyclone automatically flows into a feed trough of a hydraulic clarifier and is sent into the hydraulic clarifier by a feed pump, the slurry averagely enters each clarification tank, after solid-liquid separation of a cyclone, the overflow with the solid content of less than 1g/L enters an overflow tank, and automatically flows into a mother liquid tank by an overflow pipe; the underflow with solid content more than 200g/L meeting the feeding requirement of the vertical disc filter enters an underflow box and enters the vertical disc filter from an underflow pipe. And continuously washing the filtered fine seed filter cake with water to remove oxalate or directly adding the fine seed filter cake serving as the fine seed into a first-stage decomposition agglomeration tank, and automatically flowing the filtrate of the vertical disc filter into a mother liquor tank.

Example 1:

according to the figure 1-2, a plurality of clarification compartments of the hydraulic clarifier are fixed on a chassis, the bottom of the chassis is provided with a feed inlet, the feed inlet is connected with the inlet of each clarification compartment on the chassis, and a feed box of the clarification compartment is connected with each cyclone. The overflow ports of the cyclones are connected with an overflow tank, and the cyclone sand settling nozzles are connected with an underflow tank. That is, a plurality of swirlers connected in parallel form a single clarifier tank, and a plurality of clarifiers connected in parallel form the entire hydraulic clarifier.

The hydraulic clarifier is composed of a plurality of cabins, and each cabin contains a plurality of cyclones.

The overflow solid content of the hydraulic clarifier is not more than 1g/L, and the solid content requirement of the seed precipitation mother liquor is met.

The solid content of the bottom flow of the hydraulic clarifier is more than 200g/L, and the requirement of the lowest solid content of the feed of the vertical disc filter is met.

As shown in figure 1, the overflow of the secondary hydrocyclone automatically flows into a feed trough 1 of the hydraulic clarifier, and is sent into a feed inlet of a hydraulic clarifier 3 by a feed pump 2, slurry averagely enters each cabin of the hydraulic clarifier, after solid-liquid separation by a plurality of cyclone in the cabin, the overflow containing 0.8g/L of solid enters an overflow box of the hydraulic clarifier, and automatically flows into a mother liquid trough by an overflow pipe; the underflow which meets the feeding requirement of the vertical disc filter and contains 250g/L of solid enters an underflow box of the hydraulic clarifier and enters the vertical disc filter 4 through an underflow pipe. And continuously washing the filtered fine seed filter cake with water to remove oxalate or directly adding the fine seed filter cake serving as the fine seed into a first-stage decomposition agglomeration tank, and automatically flowing the filtrate of the vertical disc filter into a mother liquor tank.

Example 2:

this example differs from example 1 in that one or two of the multiple chambers of the hydroclarifier are on standby and slurry is averaged into each chamber of the hydroclarifier that is on-stream. When the cyclone in the cabin in the starting state is damaged, the whole cabin is isolated and overhauled, and the standby cabin is started. The rest is the same as example 1.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, extension, etc. made within the process and equipment of the present invention are included in the scope of protection of the present invention.

Claims

1. A fine seed slurry concentration device is characterized in that: the device comprises a hydraulic clarifier, wherein the hydraulic clarifier is connected with a feeding trough of the hydraulic clarifier through a feeding pump, and the feeding trough of the hydraulic clarifier is connected with a secondary hydrocyclone; the hydraulic clarifier is characterized in that a cyclone for separating slurry is arranged in the hydraulic clarifier, an overflow port of the cyclone is connected with an overflow box, a sand settling nozzle of the cyclone is connected with an underflow box, the overflow box is connected with a mother liquor tank, and the underflow box is connected with a vertical disc filter.

2. The fine seed slurry thickening apparatus of claim 1, wherein: the hydraulic clarifier is characterized in that a base plate is arranged in the hydraulic clarifier, a feed port is arranged at the bottom of the base plate, a plurality of clarifying chambers are arranged on the base plate, the feed port is communicated with inlets of the plurality of clarifying chambers, a feed box connected with the feed port is arranged in each clarifying chamber, the feed box is communicated with the plurality of cyclones respectively, and overflow ports of the cyclones in each clarifying chamber are connected with overflow boxes respectively.

3. A method for concentrating fine seed slurry is characterized in that: the overflow of the secondary hydrocyclone automatically flows into a feeding trough of the hydraulic clarifier and is sent into the hydraulic clarifier by a feeding pump, after the slurry is subjected to solid-liquid separation by a plurality of cyclones in the hydraulic clarifier, the overflow with the solid content not more than 1g/L enters an overflow tank and automatically flows into a mother liquid tank by an overflow pipe; the underflow with solid content more than 200g/L enters an underflow box, enters a vertical disc filter through an underflow pipe, and the filtered fine seed filter cake is continuously washed by water to remove oxalate or is directly added into a first-stage decomposition agglomeration tank as fine seeds.