RU2334799C1 - Method of processing of oil titanium leucoxenic concentrates - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy of rare metals, particularly to methods of processing of hard uncovered concentrates specifically to leucoxenic concentrates produced at dressing of oil bearing siliceous titanium ores of Yaregsky deposit and used for further production of artificial rutile. The method includes sintering of float concentrate at presence of additives, cooling, crumbling and dressing by way of separation of titanium oxide grains from silicates either by physic-chemical and/or mechanical methods. Prior to sintering oil titanium leucoxenic float concentrate is mixed with fuel sorption active additives for their saturation with oil from float concentrate. Sintering is performed by means of filtration burning under the mode of superadiabatic heating in a shaft type reactor. At that oil titanium float concentrate is charged into the reactor from the top together with inert additives, while from the bottom oxygen containing gas-oxidiser is supplied into the reactor by counterflow. Float concentrate is being charged at its successive flow through the heating and drying zones, through pyrolysis zone, burning and cooling zones and is discharged; while oxygen containing gas-oxidiser is supplied during the flow through these zones at inverted sequence; this gas takes part in the processes of burning and interacts with components of the concentrate producing at the final stage gas-product which consists of water steam released during drying and products of oil burning. As inert additives, recycled hard modifying additives in kind of refractory materials are used. The temperature of sintering in the burning zone is maintained within the range of 900-1300°C by means of regulating mass fractions of burning and non-burning materials charged into the reactor and oxygen supplied with gas-oxidiser.

EFFECT: upgraded chemical activity (treatability) of concentrate, increased contents of rutile phase in concentrate, increased profitability of the process.

4 cl, 1 dwg, 1 tbl

Description

The invention relates to the metallurgy of rare metals, and in particular to methods for processing difficult-to-concentrate concentrates, in particular leukoxene concentrates obtained by beneficiation of oil-bearing silicon-titanium ores, for example, characteristic of the Yarega deposit and used to further produce artificial rutile. Rutile concentrates are an invariable high-quality raw material for the production of titanium and pigment TiO ₂ , for example, by the chlorine method.

There is a known pyrometallurgical method for producing artificial (synthetic) rutile from ilmenite (see: for example, Elger GW, Kirby DE and Rhoads SC Producing Synthetic Rudle from Ilmenite by Pyrometallurgy Pilot Plan Stadies and economic Evaluadon / Rept. Invest Bur. Mines US Dep. Inter. , 1976).

According to this method, ilmenite, mixed with coke and lime, is melted in an electric arc furnace to extract most of the iron in it in the form of commodity iron and to obtain low iron-rich slag enriched with titanium dioxide. This slag is then treated with oxygen and titanium pyrophosphate.

Titanium oxides are converted to crystalline rutile; and most of the impurities present in ilmenite pass into phosphate glass. Treated slag is ground and leached with sulfuric acid to isolate rutile crystals, which are then enriched by physical methods.

In semi-industrial tests, an artificial product containing about 88 wt.% TiO ₂ and 2% Fe _total was obtained from a root type ilmenite concentrate containing about 45 wt.% TiO ₂ .

The above method for producing rutile from ilmenite concentrates is not applicable in the case of leukoxene concentrate. In leucoxene, rutile is in the form of a fine intergrowth with quartz. Leucoxene grains form a grid matrix of rutile filaments cemented with finely divided quartz. In these grids, the thickness of the yarn is usually 1-5 microns. In leucoxene concentrate, the content of TiO ₂ ranges from 45-60%, and SiO ₂ - 30-45%. In addition to titanium and silicon oxides, the leukoxene concentrate contains (%): 2.5-3.5 Fe ₂ O ₃ , 3-4.5 Al ₂ O ₃ , up to 0.5 MgO, up to 0.5 CaO, and a small amount other impurity components.

There is a method of alkaline autoclave leaching of a flotation concentrate calcined at 900-1000 ° C to obtain titanium-rich products: 71-80% TiO ₂ and 12-20% SiO ₂ (see: for example, Fedorova MN Chemical finishing of a titanium concentrate by autoclave leaching of silicic acid. In the book Titanium and its alloys, V. 9. M.: Publishing House of the USSR Academy of Sciences, 1963, p. 36-41). During additional processing of the enriched product with hydrochloric acid and its subsequent refinement on a concentration table, it is possible to increase the TiO ₂ content in it to 80-85%.

The main disadvantages of this method are the high consumption of alkaline reagent and the need for additional operations - acid leaching to increase the content of TiO ₂ in the final product.

The use of large quantities of alkali or soda, as well as the difficulty of disposing of large volumes of alkaline solutions (5-6 m ³ per 1 ton of TiO ₂ ) dramatically reduces the effectiveness of these methods for processing leucoxene concentrate to obtain TiO ₂ rich products. The high content of SiO ₂ (~ 110 g / l) in alkaline solutions does not allow to utilize these solutions with the regeneration of the used alkaline reagent. When CaO is added (to precipitate SiO ₂ ) to the solution, the pulp becomes a continuous dense mass, which is not stirred by the mixer and not filtered.

A known method of processing a leucoxene concentrate with a TiO ₂ content of 46%, including reducing calcination at a temperature of 1200-1350 ° C for 20-150 minutes, grinding the calcined concentrate to a particle size of 75 μm, mixing with concentrated sulfuric acid, heating to 200 ° C and exposure at this temperature for 1.5 hours, cooling and leaching with water (see RF patent No. 2001138, C22B 34/12, publ. 15.10.93).

The disadvantage of this method is the high energy intensity and environmental aggressiveness, the use of sophisticated technological equipment.

The closest to the claimed invention in technical essence and the achieved result is a method for producing artificial rutile from leukoxene concentrate, including roasting of flotation concentrate and cooling, autoclave leaching of calcined concentrate with NaOH solutions, filtration of leached pulp with separation into a silicate solution and titanium-containing product, and degumming of the latter leukoxene concentrate is carried out in the presence of modifying additives of iron oxide compounds in an amount e 2-3% based on Fe ₂ O ₃ (by weight of the concentrate) and is carried out in the temperature range 1450-1525 ° C, and after cooling is ground frit and subjected to preliminary desliming before leaching autoclave (RF Patent № 2,216,517, S01G 23/047 dated July 15, 2002).

With the essential features of the invention, the following combination of features coincides: a method for processing oil titanium concentrates, including roasting a flotation concentrate in the presence of additives, cooling and further grinding and enrichment by separating titanium oxide grains from silicate in a known manner.

The method has significant drawbacks: it does not allow further efficient grinding and concentration of the concentrate using other methods of physicochemical and mechanical separation of components in addition to autoclave leaching and the accompanying methods of processing products. High firing temperatures lead to the formation of cake, requiring additional processing.

However, despite a significant reduction in alkali consumption during autoclave leaching according to the known method, the main disadvantages inherent in the autoclave leaching of concentrate are not eliminated. The formation of a large volume of concentrated silicate solutions, for the disposal of which an energy-intensive operation is used, greatly increases the cost of the target product; regeneration of alkaline solutions is necessary; significant losses of titanium dioxide are possible together with other oxides with which it forms compounds.

When applying the sulfate method of enrichment of titanium-containing concentrates, problems arise associated with the difficulty of the decomposition process.

In addition, after flotation enrichment of the oil titanium ores of the Yarega deposit, the resulting flotation concentrate contains a rather large residual oil content (up to 9% in ore and up to 36% in flotation concentrate). This reduces the chemical activity of leukoxene concentrates, which, as a rule, is not taken into account in the known methods of roasting and processing of the concentrate and which significantly reduces the efficiency of the processes of further (after flotation) enrichment. At the same time, furnaces that are fired in known methods, for example, rotary tube furnaces, do not solve the problem of supplying heat to the reaction zone, they are very bulky, energy-intensive, inefficient for removing oil, and firing in them leads to significant irretrievable losses of energy raw materials.

The objective of the invention is:

deep burning (extraction) of oil from the oil-containing titanium-silicon leucoxene flotation concentrate, preparation of the latter for more efficient further enrichment of titanium-silicon concentrate due to the implementation of favorable physicochemical, mechanical and phase transformations inside the concentrate during its roasting and cooling, as well as due to creating good conditions for supplying heat to the combustion and heating zone with the simultaneous production of combustible gas, and the use of gas as fuel for heat and / or sludge electricity.

When carrying out the invention, the following technical results can be obtained:

- increases the chemical activity (opening) of the concentrate;

- increases the content of the rutile phase in the concentrate;

- the concentrate is embrittled and, if necessary, easily milled;

- the profitability of the enrichment process increases due to the use of the oil fraction contained in it in the form of combustible gas to generate heat, electricity and for its own technological needs.

This object is achieved by the fact that in the method for processing oil titanium leukoxene flotation concentrates, which includes calcining flotation concentrate in the presence of additives and cooling, as well as further grinding and enrichment by separating grains of titanium oxide from silicates by known physicochemical and / or mechanical methods, calcination is carried out by filtration combustion mode super-adiabatic heating in the reactor mine hoist, while the oil-containing flotation concentrate is loaded into the reactor from above mixed It is clear with additives, and from below the oxygen-containing oxidizing gas is fed countercurrently to the reactor, and the floc concentrate passes successively through the heating and drying zone, the pyrolysis zone, the combustion zone, the cooling zone and through the grates it enters the discharge hopper of the discharge device, and the oxygen-containing oxidizing gas is supplied from below and passes through these zones in the reverse order, while it participates in the processes of combustion and interaction with the components of the concentrate with the formation at the final stage of the passage of product gas zones in aB which includes water vapor released during drying, and evaporation of the products of pyrolysis and combustion of oil; as additives, reverse solid modifying additives are used in the form of “inert” refractory materials, as well as fuel sorption-active additives impregnated with oil from a flotation concentrate before loading it into the reactor; the firing temperature in the combustion zone is maintained within 900-1300 ° C by controlling the mass fractions of the combustible and non-combustible materials loaded into the reactor, as well as the oxygen supplied with the oxidizing gas.

In the composition of the oxidizing gas, oxygen, steam, carbon dioxide, and also recycled flue gas obtained in the process of burning oil-containing concentrates can be used together with air.

Refractory materials based on Al ₂ O ₃ , MgO, ZrO ₂ , pure, and also containing other oxides with a higher oxygen potential than those of the main oxides that specify the P0 ₂ medium are used as solid working modifying additives.

Coal, including charcoal, wood waste and other combustible hydrocarbon-containing materials, can be used as fuel sorption-active additives.

In the proposed method, the firing of the concentrate is carried out in the presence of "inert" additives - refractory materials, which loosen and separate the mass of the concentrate passing through the gasifier and allow it to freely descend. They also, setting a specific oxygen potential in the furnace, serve as modifiers and sources of rutile phase nuclei in leukoxene concentrate. Moreover, firing is carried out at temperatures of 900-1300 ° C, which also contributes to recrystallization, nucleation and enlargement of rutile grains from 1-5 to 70-250 microns. At the same time, quartz is converted into cristobalite, which forms a finely dispersed, well-crystallized microstructure. A small part of SiO ₂ binds to impurity components of the concentrate (oxides of iron, aluminum, calcium, magnesium, manganese, sodium) into silicates of complex composition. Silicates under firing conditions with cristobalite form a solid solution in the form of glass and are distributed along the boundaries between the grains of rutile and free cristobalite. When the firing product is cooled, the glass crystallizes with the release of finely dispersed crystals of cristobalite and silicates. The cooled concentrate turns into a highly porous, easy-to-grind mass. Due to this, when grinding it, most of cristobalite is easily converted into fine powder, and the other part of it together with silicates remains in the form of intergrowths with rutile grains. A sufficiently large difference in the specific gravities of rutile (4.2 g / cm ³ ) and cristobalite (2.2-2.4 g / cm ³ ) allows you to remove about 70% of SiO ₂ from the crushed material using further flotation or deslamation. After that, the content of TiO ₂ in the product can be increased to 70-90%, and the content of SiO _{2 is} reduced to 10-20%. About half of the SiO ₂ remaining in the product is in a free state, and the other half in the form of silicates.

In the chemical treatment of this product, for example, with the participation of sulfuric acid, silicates disperse and form a finely divided fraction. This helps to clean the sprouts of rutile grains. During the deslamation of the solid phase, finely dispersed silicates in the form of sludge are quite easily removed. After deslamation and drying, the content of TiO ₂ in the final product reaches 90-94%. The resulting product, the so-called "artificial rutile", contains 1.2-2.1% SiO ₂ , 3.0-4.7% Fe ₂ O ₃ , 1.5-3% Al ₂ O ₃ and without additional processing may be used as high quality raw materials for the production of titanium metal and pigment titanium dioxide by the chlorine method.

In the proposed method, the optimal firing temperature of leukoxene concentrate with additives is in the range of 900-1300 ° C, more preferably in the range of 1100-1200 ° C. Under firing conditions, recrystallization and enlargement of rutile grains begin at a temperature of 800 ° C, and gradually increase with increasing temperature. At 900 ° C, the grain size of rutile does not exceed 30 microns, which is insufficient for enrichment by mechanical methods. The formation of sufficiently large grains of rutile (from 70 to 150 microns) occurs at a temperature of 1100-1200 ° C. An increase in temperature to 1300 ° C favors the enlargement of rutile. In this case, the merging of individual rutile grains occurs with the formation of large aggregates with a size of 300-500 microns. A further increase in temperature is impractical. Firstly, this increases energy costs during firing, and secondly, at an elevated temperature, silica melts with dissolution of TiO ₂ in it due to the formation of a eutectic. This worsens the conditions for further processing and leads to a significant increase in titanium losses during sludge removal. Therefore, in order to avoid the transition of silica to a liquid state, the upper limit of the firing temperature of the concentrate must be maintained far from the appearance of a eutectic, preferably at 1300 ° C. Thus, the most acceptable firing temperature of a leucoxene concentrate with modifying additives to obtain large rutile grains can range from 900-1300 ° C.

The passage of the concentrate and reaction products through the drying, pyrolysis and cooling zones, characterized by different oxygen potentials, leads to a series of processes favorable for further enrichment. Thus, carbon and carbon monoxide contribute to the weakening of chemical bonds between the oxides in the concentrate and in the resulting oxide compounds. The excess and lack of oxygen and carbon alternating throughout the reactor zones contribute to defect formation in leukoxene concentrate. An increase in defectiveness leads to the appearance of elastic stresses; as a result, local order disturbances appear in the microvolumes surrounding the defective complex. The formation of a superstructure or shear structure is also possible. In compounds with the rutile structure, the coordination polyhedra are rearranged by rotation. Transformations with a change in primary coordination and the formation of a new type of lattice are accompanied by deep changes in the internal energy of the system. Strain transformations and reconstructive transformations with structural rearrangement are possible. Moreover, a structure with a lower coordination (SiO ₂ = 4) is relatively loose, has a higher entropy, heat capacity, and internal energy. In TiO ₂ , both irreversible transformations of one modification to another, for example, at temperatures above 700 ° C, and reversible structural transformations associated with the so-called martensitic transformations with a change in temperature can occur.

The essence of the method of processing oil-containing leukoxene concentrates is illustrated in the drawing, which shows a general diagram of the process of firing oil titanium concentrate in a vertical shaft type reactor using a known method. (A similar scheme is described in the patent of the Russian Federation No. 2116570 for solving another technical problem - the processing of hydrocarbon raw materials in order to obtain energy).

Further, the method is presented in the following example.

An oil-titanium flotation concentrate, which is supplied from the processing plant to the firing site through the pipeline in the form of pulp of the following composition, was fired:

18-22 wt.% - petroleum products,

42-46 wt.% - water,

32-36 wt.% - titanium-containing sand (mineral phase).

For the normal course of the flotation concentrate firing process by filtration combustion, it is necessary that the charge supplied to the reactor satisfy the following restrictions:

Humidity - not higher than 22%

The maximum linear size of a piece of refractory material (conventionally called "inert") is not more than 150-200 mm.

The content of small fractions (<50 mm) - not more than 50% by weight of the mass of "inert".

For the processing of oil concentrate, a mixture is prepared using solid fuel, which is used as charcoal. Charcoal content - not less than 5%.

The content of components at full load (100%) of the reactor:

- refractory refractory material (inert) - 30-40%;

- flotation concentrate (mixed with coal) - 60-70%.

The bulk of the inert during the firing process is in the reactor, moves from top to bottom in it, is removed from it and added back to the charge (see drawing), i.e. is in circulation.

The mineral phase of the flotation concentrate contains, wt.%: 45-60 TiO ₂ , 30-45 SiO ₂ , 2.5-4.0 Al ₂ O ₃ , 0.85-3.5 Fe ₂ O ₃ , 0.02-0 , 1 P ₂ O ₃ .

Before loading into the reactor 1, the flotation concentrate undergoes several processing stages: initially, the flotation concentrate in the form of pulp, consisting of the solid mineral phase of the concentrate, oil and water, enters the thickener 2 (there may be several), where the main operation of separating water from the mixture of flotation concentrate and oil is performed . Next, the resulting mixture in the form of sludge is fed into the mixer 3 (there may also be several), in which further removal of water is carried out, in addition, charcoal is produced in the mixer 3, which is produced from, for example, sawdust, and which sorb large part of the oil and helps to separate it from the water. When 5% charcoal is added to the mixture, at least half of the remaining moisture is separated, while the content of the main components in the oil titanium flotation concentrate (in oil sludge, without inert) is distributed as follows:

30-36 wt.% - petroleum products;

5-10 wt.% - water;

54-62 wt.% - titanium-containing sand (minphase);

4-6 wt.% - charcoal.

The resulting mixture of oil sludge (a mixture of flotation concentrate, water and oil) and charcoal is delivered to the feed hopper 4 using a collection conveyor, and inert is conveyed there by the conveyor. Thus prepared mixture (the content of concentrate, oil, water, charcoal and inert in it, see the Table) is loaded into the reactor 1 through a special loading device 5, which prevents the product gas from leaving the reactor into the atmosphere. In the reactor 1, under the action of its own weight, the mixture is lowered towards the gas flow. Download sequentially passes through the heating and drying zone 6, pyrolysis 7, combustion 8 and cooling 9. In the heating and drying zone 6 (T <200 ° C), the charge is dried and the light oil evaporates. In the pyrolysis zone 7 (200 <Т <800 ° С), evaporation and cracking of heavy oil fractions takes place. Evaporated oil is carried away by a stream and when the latter is cooled, they are condensed into a fine mist, which can be successfully burned to produce energy. With further lowering of the mixture containing charcoal, it enters the combustion zone 8 (900 <T <1300 ° C), where it burns in oxygen and reacts with water vapor to form carbon monoxide, carbon dioxide and hydrogen. Next, the solid residue of the mixture (concentrate sand and inert without coal and oil) is cooled in the cooling zone 9 by an air flow from ~ 1200 ° C to T <100 ° C. In the lower part of the reactor, the solid residue and ash are discharged through the grates from the reactor to the receiving hopper of the unloading device 10. In the lower part of the reactor 1, an oxidizing gas containing oxygen (for example, a mixture of air and water vapor) is passed through the cooling zone 9, reacts with coal in the combustion zone 8 and, cooling in the zones of pyrolysis 7 and drying 6, is removed from the reactor 1 already in the form of a combustible product gas. The loading rates of the charge, unloading of the solid residue and the supply of the oxidizing gas (gasifying agent) are consistent in such a way that the position of the combustion zone 8 (where the temperature is maximum) relative to the reactor 1 and the height of the charge layer remain stationary. The solid residue is sent for further processing. In this case, the solid refractory carrier is removed by dispersing the solid residue on the screen 11 (screening system) and reused in a cycle, and the concentrate is recovered in the form of sand by the screening 12 (screening system) and sent for further enrichment. The product gas released in the reactor 1 is used as fuel, for example, in a steam boiler 13. The generated heat is given to consumers, part of the heat, if necessary, is used in the process for technological needs (for example, heating the fuel in winter) and ensuring the supply of water vapor to the reactor . In addition, the oil mist after processing by known technologies can be condensed, for example, in a cyclone-condenser 14, and used as a source of hydrocarbon raw materials, and non-condensable gas as a combustible fuel gas.

The use of such reactors (gasification reactors) for firing oil titanium leucoxene concentrates allows the process of heating and gasification of oil products without supplying heat from the outside and with high energy efficiency. The energy necessary to maintain the process can be supplied by burning part of the combustible material of the oil concentrate and the coal added to the charge. At the same time, the temperature in the combustion zones is constantly regulated and maintained within the specified values. When the temperature rises above a predetermined temperature, the mass fraction of oxygen in the oxidizing gas is adjusted — it is reduced, due to which the temperature decreases. On the contrary, when the temperature in the combustion zone drops below a predetermined fraction of the flue gas in the oxidizing gas is reduced, respectively, reducing the mass fraction of combustible material in the charge and increasing the mass fraction of non-combustible material. In this case, the combustion temperature rises. The width of the combustion zone is also regulated in this way. Moreover, the range of changes in temperature and zone width can be quite wide, which allows expanding the capabilities of the proposed method for the effect of the heat of combustion accumulated in the combustion zone on a flotation concentrate of various or heterogeneous composition.

The table shows the options for a specific implementation of the method. Changes in the phase composition of the samples were controlled by optical and radiographic methods. The chemical activity (opening) was determined according to the well-known NIPROINS method at 200 ° C.

Studies have shown that the titanium dioxide content in the processed concentrate increases. In this case, titanium dioxide is represented mainly in rutile form. In addition, the chemical activity of leukoxene concentrates after firing by the proposed method is significantly increased, which can significantly increase the efficiency and economy of further enrichment of titanium-silicon concentrate and obtain, for example, high-quality pigment titanium dioxide, for example, by the chlorine method.

Oil from a titanium flotation concentrate during its roasting is completely burned to produce a high-calorie product gas, which is burned in the second stage of the two-stage process with utilization of the calorific value of various consumers.

The method can be implemented both in a batch and continuous reactor, depending on the planned volumes of oil-titanium flotation concentrates processing. In addition, the proposed method can be implemented in a similar reactor for the disposal of oil sludge and other combustible waste oil, refining and other industries in order to improve the ecology of the latter. Combustible household waste can also be recycled.

Table №№ The composition of the charge The composition of the concentrate (ref) T-firing, ° C Contents TiO ₂ after firing,% Contents oil after firing,% Cracking after firing Concentrate,% Oil% Water% Additives,% TiO ₂ % SiO ₂ % Etc. % coal inert one 33.0 22.0 5,0 5.5 34.5 58.3 35.6 6.1 800 58.4 0.01 78,2 2 34.8 19,4 5.8 5.2 34.8 55.5 40.3 4.2 900 57.8 0,0 98.3 3 36.5 19.2 4.3 5.3 34.7 52.1 43.7 4.2 1000 58.2 0,0 98.6 four 37.5 19.0 3,5 5,0 35.0 50,0 45,2 4.8 1300 56.3 0,0 98.8 5 37.9 18.9 3.2 5.8 34.2 49.8 42.6 7.6 1400 50,5 0,0 81.1

Claims (4)

1. A method of processing oil titanium leukoxene flotation concentrates, including roasting the floc concentrate in the presence of additives, cooling, grinding and enriching by separating the grains of titanium oxide from silicates by physicochemical and / or mechanical methods, characterized in that before firing the oil titanium leukoxene flotation concentrate mixes active additives for oil impregnation from flotation concentrate, firing is carried out by filtration combustion in the mode of super-adiabatic heating in re a mine-type actor, while the titanium oil flotation concentrate is loaded into the reactor from above together with inert additives, and the oxygen-containing oxidizing gas is fed countercurrently from below to the reactor, and the floc concentrate is loaded by passing it through the heating and drying zone, the pyrolysis zone, the combustion zone, the cooling zone and unload, and an oxygen-containing oxidizing gas is supplied during the passage of these zones in the reverse order and with its participation in the combustion and interaction with the components of the concentrate with the development at the final stage of a product gas consisting of water vapor generated during drying and oil combustion products, reverse solid modifying additives in the form of refractory materials are used as inert additives, the firing temperature in the combustion zone is maintained within 900-1300 ° C by regulation of the mass fractions of the combustible and non-combustible materials and oxygen fed into the reactor supplied with the oxidizing gas. 2. The method according to claim 1, characterized in that water vapor, carbon dioxide or flue gas obtained in the process of firing an oil-containing flotation concentrate are introduced into the composition of an oxygen-containing oxidizing gas. 3. The method according to claim 1, characterized in that Al ₂ O ₃ , MgO, ZrO ₂ , refractory materials based on them, or mixtures thereof with oxides with a higher oxygen potential are used as working solid modifying additives. 4. The method according to claim 1, characterized in that as fuel sorption-active additives use coal, charcoal, wood waste and / or combustible hydrocarbon-containing materials.