Processing method of red muds of alumina industry

FIELD: metallurgy.

SUBSTANCE: invention refers to non-ferrous metallurgy, and namely to complex processing of red muds of alumina industry. Processing method of red muds of alumina industry involves obtaining of red mud pulp, extraction and concentration of rich components by combination of classification and magnetic separation methods. After the pulp classification, fine-grain fraction pulp is extracted and subject to vibrocavitation treatment and further magnetic separation with extraction of magnetic and non-magnetic products. At that, magnetic product is subject to additional classification so that iron-bearing and scandium-bearing concentrates are obtained.

EFFECT: increasing the complexity degree of processing of red muds owing to increasing the extraction degree of rich components to target products - scandium-bearing concentrate and iron oxide concentrate.

4 cl, 3 tbl, 1 ex

 

The invention relates to ferrous metallurgy, namely the complex processing of red mud from alumina production.

There is a method of processing red mud from alumina production, including reductive roasting of red mud in the presence of a reducing agent (coal or toxic) at a temperature of 700-800°C, magnetic separation in a magnetic field 80-100 kA/m sintered material with obtaining iron concentrate and alumosilicates product, which then receive the scandium containing concentrate known methods (sabirianov N.A., S. p. Yatsenko - Chemical methods of complex processing of bauxite - Ekaterinburg, Ural branch of the Russian Academy of Sciences, 2006, pp. 217-218).

The disadvantages of this method are primarily related to the complexity and multi-stage process for the complex processing of red mud, is primarily due to the application at the initial stage of high-temperature firing.

The method for extracting rare earth metals, scandium and yttrium from the red mud of alumina production, which consists in the fact that the red sludge in the form of a slurry with a solid content of 50% share in density in a centrifugal field during acceleration 40-100 m/s, the flow sigalda water 3-10 l/min, with "heavy" and "light" fraction, from which the next method MAGN is based separation in magnetic field strength 400-1600 kA/m extract rare earth concentrate (RF patent 2147622, C22B 59/00, C22B 7/00).

The disadvantages of the method include the following:

- not a high yield of iron concentrate, which have a high content of Fe2O3equal to 65-70%, but the output is only 8-10%;

- low extraction of scandium oxide concentrate (contents ~0,030% or 300 g/t)of ~10%.

The closest to the technological nature, the totality of symptoms and the achieved technical result is a method of processing red mud from alumina production, including extraction and concentration of valuable components methods of classification and magnetic separation (A.S. USSR 1715874, C22B 59/00, C01F 7/02).

The method is as follows.

The original slurry the slurry is subjected to classification according to the class of particle size 40-60 μm, the slurry particle size of less than 40-60 μm (average, 50 µm) and acidified with mineral acids (HCl or H2SO4) to a pH of 1.5-4.0, maintained at the resulting pH and stirring for 10-15 min to break up the agglomerates of mineral particles and then with respect to T:W=1:6 is subjected to magnetic separation in a magnetic field 40-80 kA/m Magnetic product, the output of which is 4.0-7.0 wt.%, is a enriched in oxides of iron and scandium concentrate - Fe2O3and Sc2O3accordingly, in rednam, 70,0% and 0.035%. With an average output of the magnetic concentrate of 5.5 wt.% extraction of valuable components from the original red mud is approximately 18% and 15.5%.

The disadvantage of this method is the low level of comprehensive utilization of red mud, due to the low degree of extraction of valuable components in the target products.

The technical result of the invention is the provision of conditions for enhancing the utilization of red mud, manifested in the increase in the degree of extraction of valuable components - iron oxide and scandium in the target products.

This goal is achieved by a method of processing red mud from alumina production, which includes obtaining a slurry of pulp extraction and concentration of valuable components based on the combination of the classification methods and wet magnetic separation and differs from the previously known method that is allocated when the initial classification of the original slurry of red mud, fine-grained fraction is subjected vibrocavitational processing with subsequent wet magnetic separation at specific values of the magnetic field has been divided into magnetic and non-magnetic products and further additional classification of magnetic product with obtaining, respectively, iron and scandium-containing conc is stratov.

The above set of distinctive features provides the technical result consists in increasing the degree of complexity of processing red mud by increasing the degree of extraction of valuable components - iron oxide and scandium in the target products.

Example

20,0 DM3production of a slurry of red mud containing 6.0 kg of the solid phase composition, wt.% - 43,0 Fe3O3and 0.010 Sc2O3- subjected to sieve classification class a particle size of 50 μm. Lower intermediate - pulp particle size of less than 50 microns, containing 5.2 kg of the solid phase composition, wt.%: 47,0 Fe2O3and 0,012 Sc2O3- processed in vibrocavitational the mixer when the value of the peripheral speed of the rotor mixers ω=50,0 m/s for 20 minutes Then the slurry is directed to magnetic separation in the electromagnetic cassette filter-separator with tension (N) of the magnetic field of 700 kA/m with a separation into magnetic and non-magnetic products with output (η), respectively, and 25,0 75,0%.

Pulp magnetic product containing 1.25 kg of the solid phase (61,4% Fe2O3and 0,018 Sc2O3), and with T:W=1:5, is directed to the classification class a particle size of 20 microns.

The pulp is lower middlings particles smaller than 20 µm - filtered, the precipitate is ushitsa at a temperature of 110-120°C for 2 hours to obtain scandium-containing concentrate, containing 0.040% for Sc2O3; output concentrate 5.0% of the number of initial CABG (fraction - 50 μm).

The product particles larger than 20 microns - is (after filtering and drying) iron concentrate (60,0% Fe2O3with 80.0% of the number of magnetic product and/or 20.0 wt.% on the number of initial CABG (fraction - 50 μm).

Removing iron oxide and scandium in the target products respectively 27.5% and 19%.

In table 1-3 shows the results of experiments on complex processing of red mud in the implementation process according to the claimed invention, and beyond optimum limits.

Table 1 presents the results of the experiments in the implementation process in the optimal mode vibrocavitational processing pulp fine-grained fraction of ceteris paribus in General:

- tension (N) of the magnetic field of 700 kA/m is the Extraction of valuable components regarded end-to-end, i.e. from the content in the original red mud and taking into account the output of the fine-grained fraction (- 50 μm).

Table 1
The results of the experiments in the implementation process in the optimal mode vibrocavitational processing sludge slurry ceteris paribus the conditions
No. of experimentsProcessing optionsThe output of the magnetic product, %The content in MP, wt.%Removing components, %
ω, m/sτ minFe2O3Sc2O3Fe2O3Sc2O3
when the optimal mode
1502022,763,50,02026,032,5
2652025,061,40,01827,532,0
3802027,057,00,01527,3 29,0
4651523,658,50,01723,528,0
5652522,560,00,01624,025,0
beyond optimum limits
6402018,552,00,014of 17.018,6
7901516,557,00,01617,419,0
8651019,450,00,01317,718,0
9653017,754,50,015the 17.319,0

Thus, as can be seen from table 1, the optimal conditions vibrocavitational processing pulp fine fraction (particle size less than 50 microns), while providing an equal magnetic field strength of 700 kA/m, the achievement of the required technical result, an increase in the degree of increasing the recovery of valuable components - iron oxide and scandium in the target products is significantly higher than in the known method (prototype), are the following (op÷5): the value of the peripheral speed (ω) of the rotor under stirring 50-80 m/s and the processing time of 15-25 minutes

Beyond optimum limits parameters:

- reduce the peripheral speed ω to 40 m/s (up) or treatment duration up to 10 min (op) not only leads to reduction of the yield (η) magnetic product to ~19,0%, but also to a significant decrease of the content in the latest iron oxide up to, on average, ~51,0%, which leads to the reduction of extraction of Fe2O3to ~17.5 per cent, i.e. at the level of values obtained by a known method. This is due to insufficiency fracture of aggregates of iron-containing magnetic particles with him is gnatname particles of minerals "waste rock" (hydroelasticity sodium and hydrogenate calcium);

the increase in the peripheral speed ω to 90 m/s (AP) and/or the duration of treatment 30 min (op) reduces the output of the magnetic product to the ~of 17.0% on average, and hence the extraction of Fe2O2to the value ~of 17.0%, i.e. lower than that in the known method. This is due to pereizlucheniem particles of hematite (Fe2O3) when vibrocavitational processing in super mode, which reduces the value of the magnetic susceptibility of the primary iron-bearing mineral in the red mud.

Table 2 shows the results of carrying out the process in the optimal mode magnetic separation under other equal conditions the initial vibrocavitational processing: the value of the peripheral speed ω=65 m/s and a duration of 20 minutes

Table 2
The results of the experiments in the implementation process in the optimal mode magnetic separation ceteris paribus
No. of experimentsThe magnetic field strength kA/mThe output of the magnetic product, %Component content, %Removing the compound is, %
Fe2O3Sc2O3Fe2O3Sc2O3
when the optimal mode
1600a 21.563,50,01725,026,5
270025,061,40,01827,532,0
380027,456,50,01628,431,5
beyond optimum limits
450016,558,00,019of 17.522,5
590028,550,5/td> 0,01326,3-

As can be seen from table 2, the optimal conditions for magnetic separation viboolyavatana sludge slurry for achieving the desired technical result: the increasing complexity of the use of red mud by increasing the degree of extraction of valuable components - iron oxide and scandium in the target products are the values of magnetic field strength (op÷3) 600 to 800 kA/m

When you exit the optimum values of the process of magnetic separation:

for the lower limit is N=500 kA/m (op) observed a decrease in the output of the magnetic product to 16.5%, which leads on the one hand a very low degree of extraction of Fe2O3(weakly magnetic hematite), equal to 17.5%, and a low concentration of the oxide of scandium, equal 0,019%, considerably below the content Sc2O3in the target product by a known method (~0,035%). The latter is associated with nadaswaram at low magnetic field Sc-containing weakly magnetic mineral - chamosite;

the upper limit is N=900 kA/m (op) observed the effect of a significant decrease in the content of valuable components in the magnetic product, especially oxide of scandium - up 0,013% Sc2O3that actually is at the level of content in IP is one fine (particle size less than 50 microns) fraction 0,012%, i.e. the concentration of valuable components, almost none. It is connected with the recovery in the magnetic product with high values of magnetic field strength of the other contained in the red mud of the weakly magnetic minerals, in particular alumalite-glandular hydrogenate containing Fe2O3and Sc2O3accordingly ~25-30% Fe2O3and ~0.005% of Sc2O3that largely razboiul magnetic product.

In table 3 the results of carrying out the process in an optimal manner classification of magnetic product under other equal conditions in the previous process operations: vibrocavitational processing and magnetic separation.

Sc-mA. to-t
Table 3
The results of the experiments in the implementation process in the optimal mode classification ceteris paribus
No. of experimentsThe class of particles, micronsThe output of concentrates, %Content targeted to those %Removing the target concentrate, %
Fe-content. to-tFe2O3in Fe-sod. to theSc2O3in MRKFe2O3Sc2O3,
when the optimal mode
11518,56,562,40,03027,019,0
22020,05,060,00,04028,020,0
32521,04,057,00,04527,818,0
beyond optimum limits
41028,03,056,00,03528,7 10,5
530of 17.57,565,00,0226,515,0

As can be seen from table 3, the optimal condition classification of magnetic product is the separation of the solid phase, class of particles with sizes in the range of 15-25 μm, (op÷3) resulting in an increase in the degree of extraction of valuable components - iron oxide and scandium - target products, respectively, on average, to 27.0% and 19%.

The output of process parameter classification or lower limit of the particle size (10 μm - op)or upper limit (30 μm - op) leads to a significant reduction in the degree of extraction of scandium oxide in rare metal concentrate to ~11-15%, which is below the value of such values in the known method.

This is due to removing a faction - 10 µm hydroaluminosilicates Na2O·Al2O3·nSiO2contained in the red mud (magnetic product), the particles of which have dimensions of 1÷5 μm, and in the second case (op) is the increase in the output of scandium-containing concentrate to 7.5% by increasing the content of hematite (Fe2O3) - a mineral that does not contain the oxide of scandium, which significantly reduces the soda is the content of the last (to 0.020%) of the target product.

Now, only a process to recycle red mud from alumina production under optimal conditions: fibroepithelioma processing pulp fine-grained fraction, when values of the circumferential speed of 50-80 m/s and duration of 15-25 min, magnetic separation in a magnetic field of 600 to 800 kA/m and classification of magnetic product, class of particles 15-25 min achieve the desired technical result: increased complexity of processing red mud by increasing the degree of extraction of valuable components of the oxides of iron and scandium in the target products (concentrates), respectively, to an average of 27.5% and 19.0%, or increase, in comparison with the known invention (prototype) respectively ~8,5% and 4.0%.

1. A method of processing red mud from alumina production, including extraction and concentration of valuable components by a combination of classification and magnetic separation, characterized in that after the classification of the pulp of the original red mud emit a fine pulp fraction and subjecting it vibrocavitational processing and subsequent magnetic separation with separation of magnetic and non-magnetic products, magnetic product is subjected to additional classification with obtaining, respectively, iron and skindisorders the th concentrates.

2. The method according to claim 1, characterized in that vibrocavitational processing pulp fine-grained fraction of the class of particles of 50 microns is carried out at a circumferential speed under stirring 50-80 m/s and duration of 15-25 minutes

3. The method according to claim 1, characterized in that the magnetic separation of the treated pulp is carried out at a magnetic field strength of 600 to 800 kA/m

4. The method according to claim 1, characterized in that the classification of the pulp magnetic product are class particles 15-25 μm.



 

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