CN1239742A

CN1239742A - Dry fume purifying system for self-roasting anodic aluminium electrolysis

Info

Publication number: CN1239742A
Application number: CN 98112107
Authority: CN
Inventors: 田应甫
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-06-22
Filing date: 1998-06-22
Publication date: 1999-12-29
Anticipated expiration: 2018-06-22
Also published as: CN1083496C

Abstract

Fume is collected from the sealed self-roasting anodic electrolyzer and mixed with alumina to adsorb the harmful gases hydrogen fluoride and asphalt dust. Through gas-solid separation of the adsorbed alumina, purified gas is exhausted and the alumina containing adsorbed matter is used as electrolysis raw material and returned to the sealed self-roasting anodic electrolyzer to produce aluminum. The present invention has relatively low cost in equipment investment, operation and maintenance, can recover electrolyte, aluminum fluoride and alumina from fume to reduce raw material consumption and reduce environmental pollution.

Description

Dry fume purifying system for self-roasting anodic aluminium electrolysis

The present invention relates to a kind of purification system of aluminium electrolytic flue, particularly a kind of dry fume purifying system for self-roasting anodic aluminium electrolysis.

At present, the aluminium cell of industrial employing has two big class-cell with self baking anode and prebaked-anode type cells, the anode mix that mixes as eu-bitumen and after-smithing petroleum coke of the anode material that uses of cell with self baking anode wherein, the flue gas that produces in the production process mainly contains hydrogen fluoride, carbonic acid gas, glance coal and evaporable aluminum fluoride, the ionogen dust, aluminum oxide dust and a large amount of tar droplets, the direct discharging meeting of flue gas brings severe contamination to atmosphere, harm humans and animals and plants.Its traditional purification style purifies for the alkaline process humidifying, promptly adopt 5% aqueous sodium carbonate washing flue gas, hydrogen fluoride gas has been become to have entered liquid by water-soluble Sodium Fluoride, spray makes flue gas cool-down simultaneously, tar cohesion back in the flue gas enters liquid with dust in flue gas and floats on the surface, other direct emptyings of gas that do not react with alkali lye such as glance coal, above-mentioned wet purification process has only become the part obnoxious flavour in the flue gas salt that can be water-soluble, if the washing lotion that contains these salt and floating matter is directly discharging, become wastewater pollution source again, though some factory adopts liming and washing lotion neutralization, make in the washing lotion deleterious fluorion become water-fast Calcium Fluoride (Fluorspan) solid and filter, but still can not administer washing lotion fully, and produce deleterious solid slag again, form secondary pollution, alkali lye is to the operational outfit seriously corroded simultaneously, working cost is high, so up to the present, producer's equipment that part has been furnished with the wet purification system also can't normally move, in fact all self-roasting anodic aluminium electrolysis factory flue gases are in direct emptying state basically, cause factory's work under bad environment, plant area's ambient atmosphere is seriously polluted.But cell with self baking anode low equipment investment, half of ton aluminium under-capitalization large-scale pre-baked cell, and production and technical indication is only a little less than large-scale pre-baked cell, although so this is not found out so far as yet the method for dealing carefully with, the discharging meeting causes great pollution to environment, but still the investor is had great magnetism.

The low dry fume purifying system for self-roasting anodic aluminium electrolysis of a kind of cost that the objective of the invention is to overcome above-mentioned deficiency and provide adopts it will no longer produce secondary pollution, can once solve the smoke pollution problem effectively, up hill and dale.

The inventor collects back interpolation pure white aluminum oxide with glance coal and makes it to mix, aluminum oxide is with very fast yellowing, and have a strong tar smell, this explanation aluminum oxide powder foot couple glance coal and tar droplet have the intensive adsorption, and the aluminum oxide after the absorption still has extraordinary flowability.

Based on this point, the present invention is achieved in that a kind of dry fume purifying system for self-roasting anodic aluminium electrolysis, it is characterized in that: cell with self baking anode is airtight, collect aluminium electrolytic flue, and add aluminum oxide make it with the aluminium electrolytic flue thorough mixing with the nuisance in the absorption flue gas; Carry out gas-solid separation process again, isolated then gas directly discharges; The isolated aluminum oxide that contains adsorptive adds in the airtight cell with self baking anode as the electrolysis raw material produces primary aluminum.

Consider that aluminum oxide is to pitch, tar, hydrogen fluoride mixed gas primary sorption is incomplete, can adopt two sections absorption, also be about to carry out add aluminum oxide with the nuisance in the further adsorbed gas in the divided gas flow after the gas-solid separation, carry out gas-solid separation process once more, the gas after separating once more directly discharges; The aluminum oxide that contains adsorptive after separating once more with last time isolated the aluminum oxide that contains adsorptive and all add in the airtight cell with self baking anode and produce primary aluminum as the electrolysis raw material.If the gas cleaning effect of this moment is still unsatisfactory, also can adopt three sections or four sections also i.e. absorption of multistage more than two sections.

The present invention specifically is achieved in that the cell with self baking anode covering airtight, to cover interior flue gas by one section smoke extractor collects in the suction smoke pipe, enter first stage reactor, and to wherein dropping into alumina powder, aluminum oxide and flue gas carry out sufficient mixing and absorption process in first stage reactor, main adsorptive pitch cigarette of this section and tar droplet; Gas-solid mixture carries out gas-solid separation process in one section dust-precipitator, wherein most of aluminum oxide is separated and is entered chute, the small portion dust enters second stage reactor with divided gas flow, in second stage reactor, add fresh aluminum oxide once more, flue gas again with the aluminum oxide thorough mixing, carry out adsorption process, hydrogen fluoride gas in the main absorption flue gas, also glance coal remaining in the first stage reactor is adsorbed once more simultaneously, gas-solid mixture after two sections absorption enters two sections dust-precipitators and carries out gas-solid separation, can direct emptying up to standard through twice flue gas after being purified, twice isolated aluminum oxide that contains adsorptive all sent into electrolyzer through chute and used as raw material.

In above-mentioned one section adsorption process, a dog-house of aluminum oxide is located at one section smoke extractor exit; In above-mentioned two sections adsorption processes, the secondary batching mouth of aluminum oxide is located at the front end of second stage reactor.

Above-mentioned one section dust-precipitator can adopt cyclone, and two sections dust-precipitators can adopt bagroom.

Can find out from such scheme: the present invention does not need special or valuable equipment, and the facility investment expense is lower; And dry cleaning process etching apparatus hardly, power consumption is also less, so the equipment operation, maintenance cost is also lower; Adopt the isolated aluminum oxide that contains adsorptive of the present invention to be added to and produce primary aluminum in the electrolyzer as the electrolysis raw material, raw material and auxiliary material that adsorbed hydrogen fluoride and other fluorochemicals and dust become Aluminium Electrolysis again add in the electrolyzer, adsorbed glance coal, combustiblematerialss such as the tar high-temp liquid bath surface in electrolyzer fully burns and becomes free of contamination carbon dioxide.In a word, the present invention can purify thoroughly first flue gas, does not produce secondary pollution, simultaneously owing to reclaimed with flue gas evaporable ionogen, aluminum fluoride, aluminum oxide dust makes the major and minor raw material consumption of electrolytic process all reduce, and reaches the purpose that reduces cost, and the recycling of aluminum fluoride, the molecular ratio of self-roasting tank's aluminium electrolysis process is reduced, thereby improve the effect of current efficiency, production and technical indication is equal to mutually with large-scale pre-baked cell.

Adopt the present invention, the consumption of fluoride salt (aluminum fluoride and sodium aluminum fluoride) can reduce about 15 kg/ton, the consumption of aluminum oxide can reduce about 20 kg/ton-aluminium, because system adopts airtight recovery evaporable fluorochemical, can reduce electrolytical molecular ratio so again, reach the effect that improves current efficiency, production specifications according to present self-roasting tank, molecular ratio can be dropped to 2.4～2.5 from 2.7～2.8, reduce electrolysis temperature thus more than 10 ℃, may ultimately reach and improve current efficiency about at least 2%, realize reducing power consumption 300KWH/ ton-aluminium.To produce 10000 tons aluminium manufacturer per year is example, and producible economic benefit was in 1 year: fluoride salt is in 6500 yuan/ton, and fluoride salt can be saved 97.5 ten thousand yuan; Aluminum oxide is in 2500 yuan/ton, and aluminum oxide can be saved 500,000 yuan; Electricity price is saved 900,000 yuan of the electricity charge by 0.3 yuan/KWH; Improve current efficiency and calculate with 2%, every year can voluminous aluminium ingot 200 tons, remove cost of manufacture and relevant tax revenue after, sell the surplus value with 2000 yuan of/ton calculating, can create 400,000 yuan of benefits more; Behind the flue gas qualified discharge, factory can reduce about 200,000 yuan of environmental pollution damages every year; If the current consumption of system's operation calculates with 150KWH/ ton-aluminium, the electricity charge in a year are 450,000 yuan; Maintenance of the equipment, operator's cost of labor 1 year is in 500,000 yuan, so, 1 year yield of this system is 202.5 ten thousand yuan, and this explanation a year and a half to two year just can all reclaim the expense of input, so, adopt the present invention, not only can eliminate the pollution of aluminium manufacturer, find permanent living space for middle-size and small-size aluminium manufacturer environment, produce great social benefit, can bring huge economic benefit to aluminium manufacturer simultaneously.

The invention will be further described below in conjunction with drawings and Examples:

Fig. 1: system flowchart of the present invention.

Referring to Fig. 1 as can be known: a kind of dry fume purifying system for self-roasting anodic aluminium electrolysis, it is that cell with self baking anode 1 covering is airtight, to cover interior flue gas by one section smoke extractor 3 collects in the suction smoke pipe 2, enter first stage reactor 5, and at dog-house of one section smoke extractor, 3 exit aluminum oxide 4 input alumina powders, aluminum oxide and flue gas be thorough mixing absorption in first stage reactor 5, main adsorptive pitch cigarette of this section and tar droplet; Gas-solid mixture carries out gas-solid separation in one section cyclone 6, wherein most of aluminum oxide is separated and is entered chute 10, the small portion dust enters second stage reactor 8 with divided gas flow, and add fresh aluminum oxide once more at the aluminum oxide secondary dog-house 7 of second stage reactor 8 front ends, flue gas again with the aluminum oxide thorough mixing, hydrogen fluoride gas in the main absorption flue gas, also glance coal remaining in the first stage reactor 5 is adsorbed once more simultaneously, gas-solid mixture after two sections absorption enters cloth bag suction cleaner 9 and carries out gas-solid separation, directly discharge through twice flue gas after being purified, twice isolated aluminum oxide that contains adsorptive all sent into electrolyzer 1 through chute 10 and used as raw material.

Claims

1. dry fume purifying system for self-roasting anodic aluminium electrolysis is characterized in that: cell with self baking anode is airtight, and collect aluminium electrolytic flue, and add aluminum oxide and make it to carry out adsorption process with the aluminium electrolytic flue thorough mixing; Carry out gas-solid separation process again; Isolated then gas directly discharges, and the aluminum oxide that contains adsorptive after the separation adds in the airtight cell with self baking anode as the electrolysis raw material produces primary aluminum.

2. dry fume purifying system for self-roasting anodic aluminium electrolysis as claimed in claim 1, it is characterized in that: described adsorption process can adopt two sections absorption, be about to carry out add aluminum oxide with further absorption in the divided gas flow behind the gas-solid separation process, carry out gas-solid separation process once more; Perhaps described adsorption process can adopt the multistage absorption more than two sections.

3. dry fume purifying system for self-roasting anodic aluminium electrolysis as claimed in claim 1 or 2, it is characterized in that: cell with self baking anode (1) covering is airtight, to cover interior flue gas by one section smoke extractor (3) collects in the suction smoke pipe (2), enter in the first stage reactor (5), and to wherein dropping into alumina powder, aluminum oxide and flue gas carry out sufficient mixing and absorption process in first stage reactor (5); Gas-solid mixture carries out gas-solid separation process in one section dust-precipitator (6), wherein most of aluminum oxide is separated and is entered chute (10), the small portion dust enters second stage reactor (8) with divided gas flow, in second stage reactor (8), add fresh aluminum oxide once more, flue gas again with aluminum oxide thorough mixing adsorption process, gas-solid mixture after two sections absorption enters two sections dust-precipitators (9) and carries out gas-solid separation, directly discharge through twice flue gas after being purified, twice isolated aluminum oxide that contains adsorptive all sent into aluminium cell with self-baking anode (1) through chute (10) and used as raw material.

4. dry fume purifying system for self-roasting anodic aluminium electrolysis as claimed in claim 3 is characterized in that: in described one section adsorption process, a dog-house (4) of aluminum oxide is located at one section smoke extractor (3) exit; In described two sections adsorption processes, the secondary batching mouth (7) of aluminum oxide is located at the front end of second stage reactor (8).

5. dry fume purifying system for self-roasting anodic aluminium electrolysis as claimed in claim 3 is characterized in that: described one section dust-precipitator (6) can adopt cyclone, and described two sections dust-precipitators (9) can adopt bagroom.