CN101607725A - A kind of method that reclaims aluminum oxide and sodium oxide in the Bayer process red mud - Google Patents

Abstract

A kind of method that reclaims aluminum oxide and sodium oxide in the Bayer process red mud, step is: red mud is leached reaction in 30-70wt%NaOH solution, alkaline solution and red mud weight proportion 4: 1～8: 1, extraction temperature 180-250 ℃, extraction time 0.2-5h, leach pressure 0.3-1.8MPa, filter to such an extent that contain the alkali lye and the dealuminzation red mud of sodium aluminate; Contain alkali lye 50-100 ℃ of following crystallization of sodium aluminate, get aluminate hydrates sodium coarse-grain and crystalline mother solution, the crystalline mother solution circulation is used for leaching reaction; Aluminate hydrates sodium coarse-grain returns bayer's process production with water dissolution, through the desiliconization kind divide and calcine aluminum oxide; The calcium oxide that adds water and dealuminzation red mud weight 5-20% in the dealuminzation red mud, liquid-solid ratio 6: 1～10: 1 is taken off sodium under 100-180 ℃, and the red mud that takes off behind the sodium is used for manufacture of cement, and NaOH solution is used for leaching reaction.This method stripping temperature and pressure is lower, and digesting efficiency of alumina is up to 90%.

Description

A kind of method that reclaims aluminum oxide and sodium oxide in the Bayer process red mud

Technical field

The present invention relates to the field of production of aluminum oxide and sodium oxide, the method for aluminum oxide and sodium oxide in particularly a kind of low-temp low-pressure recovery Bayer process red mud.

Background technology

At present, the worldwide basis industry all faces worldwide energy shortage, and resource is deficient day by day, and environment protection more and more is subjected to people's attention, and for aluminum oxide industry, these challenges are all the more sharp-pointed.

China's alumina producing is a raw material with the diaspore type bauxite of indissoluble mainly, the ore of A/S＞10 only accounts for 10% according to statistics, A/S is that the ore of 7-10 accounts for 20%, and A/S to be the ore of 4-7 account for more than 60%, high alumina, high silicon, low alumina silica ratio are the valuable feature of China's bauxite.Handle A/S when the diaspore type bauxite of 4-7 with pure Bayer process, the alumina recovery rate is low, causes resource utilization low, and the economic and social benefits of aluminum oxide production process are seriously influenced.In order to improve the rate of recovery of aluminum oxide, USSR (Union of Soviet Socialist Republics) and China are devoted for years in adopting the technical study of Bayer sintering integrated process, have obtained significant achievement.But facts have proved that there is the energy consumption height to a certain extent in the integrated process Production Flow Chart, the not high drawback of Production Flow Chart complexity, production efficiency.

Alumina-producing method mainly is a sintering process in the existing recovery red mud, this method is mixed with Bayer process red mud and yellow soda ash, carrying out sintering more than 1000 ℃, obtain the solid sodium aluminate sintered product, just obtain sodium aluminate solution with the diluted alkaline stripping then, feed carbonic acid gas in the solution and promptly obtain aluminium hydroxide, (seeing Bi Shiwen " production technique of aluminum oxide " for details) used in the yellow soda ash recirculation that remains in the solution.The method that reclaims sodium oxide then is to carry out hydro-thermal reaction by add calcium oxide in red mud not reclaiming under the situation of aluminum oxide, allows sodium oxide enter liquid phase, and then reaches the purpose that reclaims sodium oxide.There are problems such as high energy consumption or the rate of recovery are low in above method, and the valuable metal that is seriously restricting red mud reclaims and comprehensive utilization.

Summary of the invention

The objective of the invention is deficiency at aluminum oxide and sodium oxide method existence in the above-mentioned existing recovery Bayer process red mud, a kind of production method that can reclaim aluminum oxide and sodium oxide in the Bayer process red mud under low-temp low-pressure is proposed, and then energy efficient and improve resource utilization effectively.

The objective of the invention is to realize by following technology.

The method of aluminum oxide and sodium oxide in the recovery Bayer process red mud provided by the invention, its step is as follows:

1) Bayer process red mud in being the NaOH aqueous solution of 30-70%, weight percent concentration is leached reaction, the weight part proportioning of described alkaline solution and Bayer process red mud is 4: 1～8: 1, the extraction temperature that leaches reaction is 180-250 ℃, leaching the reaction times is 0.2-5 hour, leaches to be incubated after reaction is finished and filters alkali lye and the dealuminzation red mud that obtains containing sodium aluminate;

2) alkali lye that contains sodium aluminate that step 1) is obtained carries out crystallization under 50-100 ℃, filter to obtain aluminate hydrates sodium coarse-grain and crystalline mother solution thereof, and the crystalline mother solution circulation is used for the leaching reaction of step 1); The aluminate hydrates sodium coarse-grain that obtains with water dissolution after, return bayer's process and produce main flow, after the desiliconization kind is divided operation aluminium hydroxide, after calcining, obtain aluminum oxide again;

3) in the dealuminzation red mud that step 1) obtains, add the calcium oxide of entry and dealuminzation red mud weight 5-20%, liquid-solid ratio is 6: 1～10: 1, sodium was taken off in reaction in 1-5 hour under temperature is 100-180 ℃, take off red mud behind the sodium is used to produce cement raw material again through washing whole mud, be circulated in step 1) in the NaOH aqueous solution that obtains and be used for leaching reaction;

The pressure of the leaching reaction of described step 1) is 0.3MPa-1.8MPa.

The method of aluminum oxide and sodium oxide has following obvious superiority in the recovery Bayer process red mud provided by the invention:

(1) extraction temperature of the present invention is 180-250 ℃, 700-800 ℃ of more traditional sintering process decline, make leaching process in, low pressure heating, can effectively cut down the consumption of energy.

(2) leaching pressure of the present invention leaches under the low pressure at 0.3MPa-1.8MPa, and it is big to have overcome facility investment, and life cycle is short, and shortcomings such as operational difficulty have reduced facility investment significantly, and make operating process be easy to carry out;

(3) dealumination process does not add any auxiliary material among the present invention, and the dealuminzation red mud amount that obtains is significantly reduced;

(4) circulation of high high alkali liquid of the present invention and isolation technique and whole process do not exist a large amount of concentration and evaporations to greatly reduce production energy consumption, have simplified production process, have reduced the equipment input, have improved industrial operability, have reduced production cost.

Embodiment

Embodiment 1

Reclaiming the Bayer process red mud aluminum oxide with method of the present invention, is example with Henan factory Bayer process red mud, and it is as follows that this Bayer process red mud is formed (wt%):

Its recycling step is:

With Bayer process red mud and weight percent concentration is that 30% NaOH solution mixes and is placed in the reactor, its weight part proportioning is Bayer process red mud: NaOH=1: 4, be warming up to 180 ℃, under 0.3MPa, react 1h, obtain containing alkali lye, the reaction product mixture of sodium aluminate and dealuminzation red mud, after reaction product to be mixed is cooled to 100 ℃, take out reactor and in 100 ℃ of baking ovens, be incubated suction filtration, separate the alkaline solution and the dealuminzation red mud that obtain containing sodium aluminate, (A is an alumina weight per-cent to A/S=0.49 in the dealuminzation red mud composition of this moment, S silicon oxide weight percent), the rate of recovery of the aluminum oxide of Bayer process red mud is 70.06%;

The alkaline solution that contains sodium aluminate (filtrated stock) that obtains is put into crystallization reactor, the causticity ratio of the crystalline mother solution that 6 hours after-filtration of crystallization obtain is elevated to 30, the causticity ratio of aluminate hydrates sodium crystal is 1.58, can make sandy alumina to sodium aluminate dissolving, desiliconization, kind branch then.

Add the calcium oxide of water and dealuminzation red mud weight 5% in the dealuminzation red mud again, its liquid-solid ratio is 6: 1, reacts 4h under 140 ℃ of conditions, and the sodium oxide concentration of whole mud is 0.6% behind the sodium for taking off of obtaining.

Embodiment 2

With Bayer process red mud and weight percent concentration is that 45% NaOH solution mixes and is placed in the reactor, its weight part proportioning is Bayer process red mud: NaOH=1: 4, be warming up to 240 ℃, under 1.3MPa, react 2h, obtain containing alkali lye, the reaction product mixture of sodium aluminate and dealuminzation red mud, after reaction product to be mixed is cooled to 100 ℃, take out reactor and in 100 ℃ of baking ovens, be incubated suction filtration, separate the alkaline solution and the dealuminzation red mud that obtain containing sodium aluminate, (A is an alumina weight per-cent to A/S=0.11 in the dealuminzation red mud composition of this moment, S silicon oxide weight percent), the rate of recovery of the aluminum oxide of Bayer process red mud is 93%;

The alkaline solution that contains sodium aluminate (filtrated stock) that obtains is put into crystallization reactor, the causticity ratio of the crystalline mother solution that 8 hours after-filtration of crystallization obtain is elevated to 32, the causticity ratio of aluminate hydrates sodium crystal is 1.65, can make sandy alumina to sodium aluminate dissolving, desiliconization, kind branch then.

Add the calcium oxide of water and dealuminzation red mud weight 10% in the dealuminzation red mud again, its liquid-solid ratio is 8: 1, reacts 3h under 150 ℃ of conditions, and the sodium oxide concentration of whole mud is 0.47% behind the sodium for taking off of obtaining.

Embodiment 3

With Bayer process red mud and weight percent concentration is that 50% NaOH solution mixes, and allocate a certain amount of aluminium hydroxide into, making the causticity ratio in the solution that obtains is 40, its weight part proportioning is Bayer process red mud: NaOH=1: 8, after insert and be warming up to 230 ℃ in the reactor, under 1.2MPa, react 2h, obtain containing alkali lye, the reaction product mixture of sodium aluminate and dealuminzation red mud, after reaction product to be mixed is cooled to 100 ℃, take out reactor and in 100 ℃ of baking ovens, be incubated suction filtration, separate the alkaline solution and the dealuminzation red mud that obtain containing sodium aluminate, (A is an alumina weight per-cent to A/S=0.49 in the dealuminzation red mud composition of this moment, S silicon oxide weight percent), the rate of recovery of the aluminum oxide of Bayer process red mud is 68.79%.

The alkaline solution that contains sodium aluminate (filtrated stock) that obtains is put into crystallization reactor, the causticity ratio of the crystalline mother solution that 16 hours after-filtration of crystallization obtain is elevated to 34, the causticity ratio of aluminate hydrates sodium crystal is 1.62, can make sandy alumina to sodium aluminate dissolving, desiliconization, kind branch then.

Add the calcium oxide of water and dealuminzation red mud weight 15% in the dealuminzation red mud again, its liquid-solid ratio is 8: 1, reacts 2h under 160 ℃ of conditions, and the sodium oxide concentration of whole mud is 0.8% behind the sodium for taking off of obtaining.

Embodiment 4

With Bayer process red mud and weight percent concentration is that 70% NaOH solution mixes, and allocate a certain amount of aluminium hydroxide into, making the causticity ratio in the solution that obtains is 40, its weight part proportioning is Bayer process red mud: NaOH=1: 5, after insert and be warming up to 250 ℃ in the reactor, under 1.7MPa, react 3h, obtain containing alkali lye, the reaction product mixture of sodium aluminate and dealuminzation red mud, after reaction product to be mixed is cooled to 100 ℃, take out reactor and in 100 ℃ of baking ovens, be incubated suction filtration, separate the alkaline solution and the dealuminzation red mud that obtain containing sodium aluminate, (A is an alumina weight per-cent to A/S=0.23 in the dealuminzation red mud composition of this moment, S silicon oxide weight percent), the rate of recovery of the aluminum oxide of Bayer process red mud is 85.31%.

The alkaline solution that contains sodium aluminate (filtrated stock) that obtains is put into crystallization reactor, the causticity ratio of the crystalline mother solution that 16 hours after-filtration of crystallization obtain is elevated to 35, the causticity ratio of aluminate hydrates sodium crystal is 1.672, can make sandy alumina to sodium aluminate dissolving, desiliconization, kind branch then.

Add the calcium oxide of water and dealuminzation red mud weight 15% in the dealuminzation red mud again, its liquid-solid ratio is 10: 1, reacts 2h under 180 ℃ of conditions, and the sodium oxide concentration of whole mud is 0.27% behind the sodium for taking off of obtaining.

Claims (1)

1, a kind of method that reclaims aluminum oxide and sodium oxide in the Bayer process red mud, its step is as follows:

1) Bayer process red mud in being the NaOH aqueous solution of 30-70%, weight percent concentration is leached reaction, the weight part proportioning of described alkaline solution and Bayer process red mud is 4: 1～8: 1, the extraction temperature that leaches reaction is 180-250 ℃, leaching the reaction times is 0.2-5 hour, leaches to be incubated after reaction is finished and filters alkali lye and the dealuminzation red mud that obtains containing sodium aluminate;

2) alkali lye that contains sodium aluminate that step 1) is obtained carries out crystallization under 50-100 ℃, filter to obtain aluminate hydrates sodium coarse-grain and crystalline mother solution thereof, and the crystalline mother solution circulation is used for the leaching reaction of step 1); The aluminate hydrates sodium coarse-grain that obtains with water dissolution after, return bayer's process and produce main flow, after the desiliconization kind is divided operation aluminium hydroxide, after calcining, obtain aluminum oxide again;

3) in the dealuminzation red mud that step 1) obtains, add the calcium oxide of entry and dealuminzation red mud weight 5-20%, liquid-solid ratio is 6: 1～10: 1, sodium was taken off in reaction in 1-5 hour under temperature is 100-180 ℃, take off red mud behind the sodium is used to produce cement raw material again through washing whole mud, be circulated in step 1) in the NaOH aqueous solution that obtains and be used for leaching reaction;

The pressure of the leaching reaction of described step 1) is 0.3-1.8MPa.