CN218810378U - Red mud separation and washing system for reducing alumina hydrolysis loss - Google Patents
Red mud separation and washing system for reducing alumina hydrolysis loss Download PDFInfo
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- CN218810378U CN218810378U CN202120849905.1U CN202120849905U CN218810378U CN 218810378 U CN218810378 U CN 218810378U CN 202120849905 U CN202120849905 U CN 202120849905U CN 218810378 U CN218810378 U CN 218810378U
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Abstract
The utility model belongs to the technical field of aluminium oxide production, concretely relates to reduce red mud separation washing system of aluminium oxide hydrolysis loss. The system comprises a high-temperature separator, a high-temperature primary washer, a high-temperature secondary washer, a heat exchanger, a double-pipe heat exchanger, a normal-pressure tertiary washing settling tank and a normal-pressure quaternary washing settling tank, wherein all the stages are connected through a pipeline; the high-temperature liquid-solid separation, heat exchange and cooling, high-temperature washing and normal-pressure washing and sedimentation of the dissolved ore pulp are realized through the high-temperature separator, the two-stage washer of the heat exchanger and the two-stage sedimentation tank, circulation is formed at each stage, the Nk value of the discharged red mud liquid attached can be effectively reduced, the hydrolysis loss of alumina is reduced, the utilization rate of materials at each stage can be improved, the consumption of aluminum ore soil is saved, and the production cost of enterprises is reduced.
Description
Technical Field
The utility model belongs to the technical field of aluminium oxide production, concretely relates to reduce red mud separation washing system of aluminium oxide hydrolysis loss.
Background
At the present stage, alumina factories in China mostly adopt a Bayer process, and a red mud separation and washing process exists in the Bayer process. At present, a conventional mode adopted for the red mud separation and washing procedure is to adopt a flat-bottom settling tank or a deep cone settling tank, the washing temperature is set to be about 95 ℃, the procedure flow is that the overflow of the settling separation tank automatically flows to a control filtration workshop, the underflow enters the washing settling tank to carry out 4~6 times of reverse washing, and the washed discharged red mud is sent to a red mud filter-pressing workshop to carry out filter-pressing.
However, the red mud separation and washing system and the red mud separation and washing process cause alumina hydrolysis loss in the washing process, particularly, the red mud is reversely washed for 4-6 times in the washing and settling tank, the process has high Rp solution, low temperature, long time and low caustic alkali concentration in the solution, so that the alumina is particularly easy to separate out from the sodium aluminate solution, the hydrolysis loss is large, and the yield of the alumina is reduced.
Disclosure of Invention
There is red mud in the subsider to present red mud separation washing system through many times reverse washing, leads to the alumina easily to appear, defect and the problem that the loss of hydrolysising is big, the utility model provides a can reduce red mud separation washing system of alumina hydrolysis loss.
The utility model provides a scheme that its technical problem adopted is: a red mud separating and washing system for reducing alumina hydrolysis loss comprises a high-temperature separator, a high-temperature primary washer, a high-temperature secondary washer, a heat exchanger, a double-pipe heat exchanger, a normal-pressure three-time washing and settling tank, a normal-pressure four-time washing and settling tank and a connecting pipeline;
the inlet of the high-temperature separator is connected with the last-stage flash evaporation discharge outlet, the underflow port of the high-temperature separator is connected with the inlet of the high-temperature primary washer through a connecting pipeline, the underflow port of the high-temperature primary washer is connected with the inlet of the high-temperature secondary washer, the discharge port of the high-temperature secondary washer is connected with the inlet of the double-pipe heat exchanger, the outlet of the double-pipe heat exchanger is connected with the inlet of the normal-pressure tertiary washing settling tank, the underflow port of the normal-pressure tertiary washing settling tank is connected with the inlet of the normal-pressure washing settling tank, and the underflow port of the normal-pressure quaternary washing settling tank is connected with the alumina red mud filter press through a pump; the overflow mouth of ordinary pressure quartic washing settling tank links to each other with the washing import of ordinary pressure cubic washing settling tank, the overflow mouth of ordinary pressure cubic washing settling tank links to each other with the cold flow layer import of heat exchanger, the cold flow layer export of heat exchanger links to each other with the washing import of high temperature secondary scrubber, the overflow mouth of high temperature secondary scrubber links to each other with the washing import of high temperature primary scrubber, the scrubber overflow mouth of high temperature primary scrubber links to each other with high temperature separator's dilution import, high temperature separator's overflow mouth links to each other with heat exchanger heat flow layer import, the heat flow layer export of heat exchanger sends the fine pure liquid to the alumina decomposition workshop section through the connecting tube.
According to the red mud separation and washing system for reducing the alumina hydrolysis loss, the heat exchanger is a plate heat exchanger, a tube heat exchanger or a double-tube heat exchanger.
In the red mud separation and washing system for reducing the alumina hydrolysis loss, the high-temperature separator is a pressure decanter.
In the red mud separating and washing system for reducing the alumina hydrolysis loss, the red mud slurry of the double-pipe heat exchanger is a pipe side, and the preheating medium channel is a shell side.
The utility model has the advantages that: the red mud separating and washing system of the utility model is provided with the high-temperature separating washer, the heat exchanger, the two-stage high-temperature washer and the two-stage normal-pressure washing settling tank, so that the ore pulp flashed out from the last stage of the ore pulp is mixed and diluted with the liquid overflowed from the high-temperature primary washer, and the liquid and the solid of the ore pulp are separated; the separated overflow solution and the overflow solution of the normal-pressure tertiary washing and settling tank exchange heat through a heat exchanger to reduce the temperature of the overflow solution of the high-temperature separator so as to facilitate the next step of cooling and decomposition; the separated red mud enters a high-temperature primary washer and a high-temperature secondary washer through a bottom flow port, and the Nk value of the red mud attached liquid in the process is reduced through twice counter-current washing, so that the total amount of alumina in the red mud attached liquid can be effectively controlled, and the hydrolysis loss is avoided. The underflow discharged from the underflow port of the high-temperature secondary washer enters a double-pipe heat exchanger to perform indirect countercurrent heat exchange with the evaporation stock solution, so that the temperature of the underflow red mud slurry of the high-temperature secondary washer is reduced, the cooled red mud slurry sequentially enters an atmospheric pressure three-time washing and settling tank and an atmospheric pressure four-time washing and settling tank, and the Nk value of the red mud attaching solution is further reduced after two times of countercurrent washing, so that the loss of sodium chloride in the red mud attaching solution can be effectively controlled, the environment is more environment-friendly, and the device can greatly reduce the hydrolysis loss of alumina through two-stage high-temperature washing and two-stage atmospheric pressure settling, and can save a large amount of bauxite; the overflow solution of the high-temperature separator and the overflow solution of the normal-pressure washing and settling tank exchange heat through the heat exchanger, so that mutual utilization of energy can be realized, and the raw material cost and the operation cost of an alumina plant are reduced.
The high-temperature separator is adopted, so that the separation and washing retention time of slurry is shortened, the contact time of red mud and solution is reduced, and the loss of aluminum oxide can be further reduced; the separated underflow slurry can obtain underflow slurry with higher solid content, which is beneficial to improving the washing efficiency; the pure liquid of aluminium oxide that the overflow liquid of overflow stream obtained after the heat exchanger cooling can directly get into the decomposition process and decompose, can cancel the filterable leaf filter of control, simplifies whole flow, reduces the lime quantity, accords with the environmental protection requirement, reduces the running cost.
Drawings
Fig. 1 is a schematic diagram of equipment connection of the red mud separation system of the utility model.
Fig. 2 is a flow chart of the separation washing process of the present invention.
Reference numbers in the figures: 1 is a high-temperature separator, 2 is a high-temperature primary washer, 3 is a high-temperature secondary washer, 4 is a heat exchanger, 5 is a double-pipe heat exchanger, 6 is a normal-pressure three-time washing settling tank, 7 is a normal-pressure four-time washing settling tank, 8 is a final-stage flash evaporation discharge of dissolved ore pulp, 9 is an evaporation stock solution, 10 is an evaporation stock solution after temperature rise, 11 is red mud washing water, 12 is discharged red mud, and 13 is a refined liquid.
Detailed Description
Because used equipment of present Bayer process production aluminium oxide washing workshop section and process cause the washing in-process aluminium oxide hydrolysis loss great to take certain aluminium oxide factory in China as an example, the aluminium oxide loss is 1.5-3.6%, the utility model provides a can reduce red mud separation washing system of aluminium oxide hydrolysis loss, this system can show the hydrolysis loss that reduces aluminium oxide washing workshop section through the reasonable setting to equipment. The present invention will be further described with reference to the accompanying drawings and examples.
Example 1: the red mud separating and washing system for reducing alumina hydrolysis loss of the embodiment, as shown in fig. 1, includes a high-temperature separator 1, a high-temperature primary washer 2, a high-temperature secondary washer 3, a heat exchanger 4, a double-pipe heat exchanger 5, a normal-pressure tertiary washing settling tank 6, a normal-pressure quaternary washing settling tank 7 and a connecting pipeline, wherein the high-temperature separator 1 is provided with a steam outlet inlet, a dilution inlet and an overflow port, and the lower end is provided with a bottom flow port; the high-temperature primary washer 2 and the high-temperature secondary washer 3 are respectively provided with a liquid inlet, a discharge hole, a washing inlet and an overflow hole; the heat exchanger 4 is provided with a heat flow layer inlet and a heat flow layer outlet; the red mud slurry in the double-pipe heat exchanger is a pipe pass, and the preheating medium channel is a shell pass; the normal pressure three-time washing and settling tank and the normal pressure four-time washing and settling tank are respectively provided with an inlet, a bottom flow port and an overflow port.
Wherein the inlet of the high-temperature separator 1 is connected with the final-stage flash evaporation discharge outlet, the underflow port of the high-temperature separator 1 is connected with the inlet of the high-temperature primary washer 2 through a connecting pipeline, the underflow port of the high-temperature primary washer 2 is connected with the inlet of the high-temperature secondary washer 3, the discharge port of the high-temperature secondary washer is connected with the inlet of the double-pipe heat exchanger, the outlet of the double-pipe heat exchanger 5 is connected with the inlet of the normal-pressure tertiary washing settling tank, the underflow port of the normal-pressure tertiary washing settling tank 6 is connected with the inlet of the normal-pressure quaternary washing settling tank to send the tertiary-washing underflow liquid into the normal-pressure quaternary washing settling tank; the bottom flow port of the normal-pressure four-time washing and settling tank 7 is connected with an alumina red mud filter press through a pump so as to send the discharged red mud 12 to a filter pressing stage.
The overflow port of the normal-pressure four-time washing and settling tank is connected with the washing inlet of the normal-pressure three-time washing and settling tank, so that two times of countercurrent washing are realized; an overflow port of the normal-pressure tertiary washing settling tank is connected with a cold flow layer inlet of the heat exchanger so as to exchange heat with overflow liquid of the high-temperature separator and cool the overflow liquid, and the cooled refined pure liquid is pumped to an alumina decomposition working section; the outlet of the cold flow layer of the heat exchanger is connected with the washing inlet of the high-temperature secondary washer, the overflow port of the high-temperature secondary washer 3 is connected with the washing inlet of the high-temperature primary washer 2, the overflow port of the high-temperature primary washer is connected with the diluting inlet of the high-temperature separator 1, the overflow port of the high-temperature separator is connected with the inlet of the heat flow layer of the heat exchanger, and the outlet of the heat flow layer of the heat exchanger sends the refined pure liquid 13 to the alumina classifier through a connecting pipeline.
The operation procedures of the system in the whole red mud separation and washing process are as follows:
1. final-stage flash evaporation discharge high-temperature liquid-solid separation of dissolved ore pulp: dissolving ore pulp (Nk is generally 180 to 300g/L, rp is 1.13 to 1.20) at 125 to 135 ℃ from the last stage flash evaporation of the dissolving ore pulp, the dissolving ore pulp is pumped into a feed inlet of a high-temperature separator, a dilution inlet of the high-temperature separator and overflow liquid discharged from an overflow port of a high-temperature primary washer in the process of the step 3 are subjected to high-temperature mixing dilution, the overflow liquid of the high-temperature separator enters the step 2, and the bottom flow enters the step 3; the step can realize the high-temperature separation of the red mud pulp, the separated overflow solid content can reach 15mg/L, and the underflow solid content can reach 42%.
2. Heat exchange and temperature reduction of the separation solution: and (3) exchanging heat between overflow liquid discharged from an overflow port of the high-temperature separator in the step (1) and overflow liquid discharged from an overflow port of the normal-pressure three-time washing and settling tank in the step (5), cooling the temperature of the overflow liquid of the high-temperature separator in the step (1) from 125-135 ℃ to 105-115 ℃, preheating the temperature of the overflow solution of the normal-pressure three-time washing and settling tank in the step (5) from 94 ℃ to 120 ℃, and then entering the step (3). The cooled pure solution can be directly pumped into an alumina decomposition section for further cooling and decomposition, the lime consumption is reduced, and the flow is simplified.
3. Separating red mud slurry and washing at high temperature: underflow red mud slurry discharged from a underflow port of the high-temperature separator in the process of the step 1 sequentially enters a high-temperature primary washer and a high-temperature secondary washer, the high-temperature washing temperature is controlled to be about 120 ℃, underflow liquid of the high-temperature secondary washer enters a step 4, two stages of high-temperature washers in the step are washed in a countercurrent mode for two times, the Nk value of red mud attached liquid can be enabled to be less than or equal to 35g/L, the red mud attached liquid is further reduced, the content of aluminum oxide in the red mud attached liquid can be effectively controlled to enter the step 4, and hydrolysis loss is reduced.
4. Separating red mud slurry for heat exchange and cooling: and 3, allowing the high-temperature secondary washing underflow red mud slurry to enter a double-pipe heat exchanger to perform indirect countercurrent heat exchange with the evaporation stock solution, so that the temperature of the underflow red mud slurry of the high-temperature secondary washing device is reduced from about 120 ℃ to about 95 ℃, allowing the red mud slurry after temperature reduction to enter a step 5, preheating the evaporation stock solution sent from an evaporation section of an alumina plant from about 84 ℃ to about 90 ℃, allowing the evaporation stock solution after temperature increase to enter an evaporation station of the alumina plant for evaporation concentration, wherein the double-pipe heat exchanger can also adopt a wide-runner heat exchanger.
5. Separating red mud slurry and washing at normal pressure: and (3) allowing the red mud slurry at the temperature of about 95 ℃ discharged from the double-pipe heat exchanger in the step (4) to enter a normal-pressure three-time washing and settling tank and a normal-pressure four-time washing and settling tank, wherein normal-pressure washing adopts two-time countercurrent washing (the specific times can be determined according to the Nk of the discharged red mud attached liquid and can be more than 2 times), the step can enable the Nk of the red mud attached liquid to be less than or equal to 4g/L so as to further reduce the Nk, washing water of the red mud at the temperature of 95 ℃ under normal pressure is sent to a hot water station working section of an alumina plant, the discharged red mud is sent to a red mud filter-pressing working section of the alumina plant by a pump at the bottom flow of the normal-pressure four-time washing and settling tank, and overflow discharged from an overflow port of the normal-pressure three-time washing and settling tank is sent to the step (4).
The utility model discloses a red mud separation washing system can realize the circulation of materials at different levels through going on of above-mentioned process to realize the utilization maximize of materials at different levels, reduce the loss of hydrolysis in the washing process, reduce the consumption of bauxite, improve the output of aluminium oxide, reduce the running cost of aluminium oxide factory.
Claims (4)
1. The utility model provides a reduce red mud separation washing system of alumina hydrolysis loss which characterized in that: the device comprises a high-temperature separator, a high-temperature primary washer, a high-temperature secondary washer, a heat exchanger, a double-pipe heat exchanger, a normal-pressure three-time washing settling tank, a normal-pressure four-time washing settling tank and a connecting pipeline; the inlet of the high-temperature separator is connected with the discharge port of the last stage flash evaporation, the underflow port of the high-temperature separator is connected with the inlet of the high-temperature primary washer through a connecting pipeline, the underflow port of the high-temperature primary washer is connected with the inlet of the high-temperature secondary washer, the discharge port of the high-temperature secondary washer is connected with the inlet of the double-pipe heat exchanger, the outlet of the double-pipe heat exchanger is connected with the inlet of the normal-pressure tertiary washing settling tank, the underflow port of the normal-pressure tertiary washing settling tank is connected with the inlet of the normal-pressure washing settling tank, and the underflow port of the normal-pressure quaternary washing settling tank is connected with the alumina red mud filter press through a pump; the overflow mouth of ordinary pressure quartic washing settling tank links to each other with the washing import of ordinary pressure cubic washing settling tank, the overflow mouth of ordinary pressure cubic washing settling tank links to each other with the cold flow layer import of heat exchanger, the cold flow layer export of heat exchanger links to each other with the washing import of high temperature secondary scrubber, the overflow mouth of high temperature secondary scrubber links to each other with the washing import of high temperature primary scrubber, the scrubber overflow mouth of high temperature primary scrubber links to each other with high temperature separator's dilution import, high temperature separator's overflow mouth links to each other with heat exchanger heat flow layer import, the heat flow layer export of heat exchanger sends the fine pure liquid to the alumina decomposition workshop section through the connecting tube.
2. The red mud separation washing system for reducing alumina hydrolysis loss according to claim 1, characterized in that: the heat exchanger is a plate heat exchanger, a tube heat exchanger or a sleeve heat exchanger.
3. The red mud separation washing system for reducing alumina hydrolysis loss according to claim 1, characterized in that: the high temperature separator is a pressure decanter.
4. The red mud separation washing system for reducing alumina hydrolysis loss according to claim 1, characterized in that: the red mud slurry of the double-pipe heat exchanger is a pipe side, and the preheating medium channel is a shell side.
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| CN202120849905.1U CN218810378U (en) | 2021-04-24 | 2021-04-24 | Red mud separation and washing system for reducing alumina hydrolysis loss |
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| CN202120849905.1U CN218810378U (en) | 2021-04-24 | 2021-04-24 | Red mud separation and washing system for reducing alumina hydrolysis loss |
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