RU2432318C1 - Method of producing powdered aluminium hydroxide (versions) and aluminium oxide - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemistry and can be used to produce powdered aluminium hydroxide and aluminium oxide. According to the first version, hydrargillite undergoes thermochemical and/or mechanochemical activation. The activation product is washed on a press filter at pH less than 9 and water is then added to the washed activation product in ratio solid:liquid equal to 1:(8-10). The obtained suspension is spray dried at 170-200°C. In the second version, the activation product is plasticised at pH 2-3 and temperature 140-160°C and water is then added to the plastification product until achieving solid:liquid ratio in the suspension of 1:(7.5-15), and the suspension is taken for spray drying at temperature 180-210°C. Aluminium hydroxide powder obtained using said method is annealed at temperature 450-650°C.

EFFECT: invention enables to obtain products of different phase composition.

5 tbl, 1 dwg, 16 ex

Description

The present invention relates to the refining and petrochemical industries, in particular to the production of refining and petrochemical catalysts, including catalysts for hydrofining of petroleum fractions. The carrier of these catalysts is alumina, preferably γ-modifications, less often η-modifications. The precursor of γ-Al ₂ O ₃ is alumina monohydrate of boehmite or pseudoboehmite structure:

Al ₂ O ₃ × XH ₂ O (where x≥1).

The precursor of η-Al ₂ O ₃ is the alumina trihydrate of the bayerite structure Al ₂ O ₃ × 3H ₂ O.

The industrial production of γ-Al ₂ O ₃ and the boehmite precursor Al ₂ O ₃ × ХН ₃ О, as well as η-Al ₂ O ₃ and the precursor Al ₂ O ₃ × 3Н ₃ О of the bayerite form, includes a method of reprecipitation of alumina trihydrate (in form of hydrargillite, or gibbsite), characterized by a high consumption of chemically purified water (up to 250 m ³ / t of product) and a large volume of wastewater.

A method for the production of active hydroxide and alumina according to a low-drain or almost drainless scheme is based on the hydrothermal treatment of the product of thermochemical and / or mechanical activation of hydrargillite (gibbsite) [1. K.N. Irisova, T. S. Kostromina, B. K. Nefedov “Carriers of Hydrotreating Catalysts Based on Active Alumina”, vol. review, TsNIITE neftekhim, 1983]; 2. K.N. Irisova, V.O. Meinzer, V.A. Pronin “Plasticization of the product of mechanochemical activation of hydrargillite” in Sat. Scientific fundamentals of the preparation and technology of catalysts, abstracts of reports of the All-Union Meeting, Minsk, 1989].

The main stages of this method:

- thermochemical (TXA) and / or mechanochemical (MXA) activation of hydrargillite; thermochemical activation of hydrargillite is carried out in the mode of pulsed heating in a catalytic generator in a fluidized bed of a solid catalyst [1]. A special device has been developed for the thermal shock treatment of bulk materials on a heated working surface (plate) without a catalyst [3. Pat. RF No. 2186616] used to activate hydrargillite [4. Pat. RF No 2237018; 5. Pat. RF №2234460]. Mechanochemical activation of hydrargillite is carried out in units with shock loading on the granules of the material [6. Pat. RF №1586056 "Method for the production of active aluminum hydroxide", 1988];

- hydrothermal treatment of activated hydrargillite, resulting in a paste of aluminum hydroxide - the precursor of active alumina. Depending on the conditions of hydrothermal treatment (temperature, pH, duration) receive aluminum hydroxide pseudoboehmite structure [5. Pat. RF №2234460] and γ-Al ₂ O ₃ based on it or aluminum hydroxide bayerite structure and η-Al ₂ O ₃ based on it [4. Pat. RF №2237018]. At the stage of plasticization of the product TXA and / or MXA of gibbsite, an additive is introduced into it [6. Pat. RF No. 1721990];

- the formation of aluminum hydroxide in a form convenient for conversion to aluminum oxide: extrusion as a part of various molding materials with subsequent calcination or removal of liquid from the paste (practically dispersion of boehmite) by heating, followed by grinding to a powder state [7. Pat. RF No. 2342321]; or spray drying an aqueous suspension of a plasticization product [8. Pat. RF №2167818] to obtain a hydroxide powder.

One of the problems in the production of active aluminum hydroxide through the plasticization of the product TXA / MXA hydrargillite is its high content of sodium oxide impurity (up to 0.6 wt.%).

It should be noted that the requirements for the depth of purification from impurities of sodium aluminum oxide as a component of catalysts and adsorbents vary widely.

For adsorbent desiccants, the content of sodium oxide is allowed up to 0.4-0.6 wt.%.

For a number of catalysts (for example, for the gasoline reforming process), the permissible content of sodium oxide is not more than 0.02 wt.%.

The famous "Method of purification of gibbsite from sodium" [9. Pat. RF №1783744], which allows to reduce the content of sodium oxide in gibbsite to 0.003 wt.% By simultaneous grinding in an aqueous suspension and washing on a disintegrator. The disadvantage of this method is the need to use a special apparatus-disintegrator, which limits its use.

For the considered method of producing aluminum oxides and hydroxides, an admixture of sodium oxide plays an important role, since the pH value determines the direction of the recrystallization process (see [4, 5]).

The current tendency to use powdered hydroxides and aluminum oxides in the production of catalysts is due to a number of circumstances, including the possibility of controlling the mechanical and catalytic properties of the catalysts using alumina powders in various proportions [10. Pat. RF №2229934].

Known methods for producing alumina powders for the production of hydrotreating catalysts by grinding extrudates of alumina obtained by various hydrargillite reprecipitation schemes [11. A.S. USSR No. 701700, A.S. USSR No. 914081]. The disadvantages of these methods are, firstly, the large volume of wastewater at the stage of production of aluminum hydroxides, and secondly, the technologically difficult operation of grinding calcined extrudates in ball mills: high energy consumption, long duration, and low strength of catalyst granules based on aluminum oxide powders .

The closest in technical essence and the achieved effect to the proposed technical solution is a method for producing powdered aluminum hydroxide by spray drying a diluted suspension of plasticization product [8. Pat. RF №2167818].

The method [8] includes thermochemical activation of hydrargillite, washing from sodium, plasticizing the suspension at pH 1-4 at a temperature of 130-200 ° C for 6-15 hours, spray drying the plasticization product in the form of a suspension with a pH of 4-10.

The disadvantages of this method [8] are:

- washing the product of TCA from sodium oxide by decantation, which is not amenable to control over time, requires large amounts of water and is accompanied by large losses of the target most finely divided part of the material when sludge is drained;

- a narrow range of powdered products, in fact only monohydrate in the form of boehmite; in the synthesis of catalyst supports, there is a need for powders of different fineness and different phase composition.

The purpose of this technical solution is to develop a method for producing powders of hydroxides and aluminum oxides of various phase compositions based on the product TXA / MXA hydrargillite with minimal losses with controlled washing from sodium oxide, with spray drying of hydrargillite activation products and plasticization products and their subsequent calcination.

This goal is achieved by a method for producing powders of hydroxides and aluminum oxides, including thermochemical and / or mechanochemical activation of hydrargillite, washing, plasticization, spray drying, characterized in that washing by filtering the activation product is carried out at pH <9, and washing the plasticization product at pH> 7 ,5; aluminum hydroxide powders are obtained by spray drying aqueous suspensions of the activation product at a ratio of solid: liquid 1: (8 ÷ 10) and plasticization product at a ratio of 1: (7 ÷ 15); aluminum oxide powders are obtained by calcining aluminum hydroxide powders at a temperature of 450 ÷ 650 ° C.

Distinctive features of the proposed method for producing powders of hydroxides and aluminum oxides are:

- washing the product TXA / MXA hydrargillite by suspension in water, taking into account the colloidal properties of the aqueous suspension of aluminum hydroxide, namely, the value of the isoelectric point pH ~ 9.1 [12. K.N. Irisova, L.I. Pavlova, V.O. Mainzer. Development of a waste-free and waste-free technology of catalyst supports and adsorbents based on active alumina. Mechanochemical activation of hydrargillite, in Sat. scientific works “New processes and oil refining products”. - M .: VNIIOENG, 1989, pp. 13-20], which allows to intensify the washing process by lowering the pH of the supply water below 9.0 and subsequent washing on the filter;

- washing the plasticization product, characterized by pH 2 ÷ 3,5, by suspension in water at pH> 7.5 and subsequent washing on the filter;

- spray drying of aqueous suspensions of the activation product of hydrargillite with a ratio of solid: liquid (8:10) and plasticization product with a ratio of 1: (7 ÷ 15);

- calcination of powders of aluminum hydroxide at a temperature of 450-650 ° C.

The proposed method for producing powdered hydroxides and aluminum oxides is described by the attached scheme (see drawing).

The main route: the product TXA / MXA of hydrargillite → plasticization → spray drying → calcination has no effluents and requires the cost of process water for the plasticization and spray drying stage up to 10 m ³ per 1 ton of Al ₂ O ₃ .

Products: aluminum hydroxides of boehmite or bayerite form or mixtures thereof, aluminum oxides γ-Al ₂ O ₃ and η-Al ₂ O _3, or mixtures thereof with an admixture of amorphous phases.

Route for amorphized products:

(A) product TXA / MXA hydrargillite → calcination does not have effluents, does not require water; the product is amorphous alumina mixed with γ-Al ₂ O ₃ .

Route for pure and ultrapure products:

(B) the product TXA / MXA of hydrargillite → flushing-1 → spray drying → calcination requires water of 20-30 m ³ / t Al ₂ O ₃ and has wastewater in a volume of 10-15 m ³ / t Al ₂ O ₃ ; products - aluminum hydroxide of a bayerite structure with an admixture of boehmite and an amorphous phase, aluminum oxide η-Al ₂ O ₃ mixed with γ-Al ₂ O ₃ and amorphous oxide.

(B ₁ ) product TXA / MXA hydrargillite → flushing-1 → plasticization → spray drying → calcination; products - pure aluminum hydroxides of boehmite or bayerite structure or mixtures thereof, pure γ-Al ₂ O ₃ and η-Al ₂ O ₃ oxides and mixtures thereof;

(B ₂ ) TXA / MXA product of hydrargillite → washing-1 → plasticization → washing-2 → spray drying → calcination; products - ultrapure aluminum hydroxides of boehmite or bayerite structure or mixtures thereof, ultrapure aluminum oxides γ-Al ₃ O ₂ or η-Al ₂ O ₃ and mixtures thereof.

From consideration of the complex conditions for obtaining powders of hydroxides and aluminum oxides and their phase composition according to the proposed technical solution, it follows that it has the signs of "novelty" and "significant differences".

The following are examples of technical solutions that illustrate it, but are not limited to.

Raw materials.

1. Hydrargillite (gibbsite) - aluminum oxide trihydrate

the content of Na ₂ O - 0.48 wt.%,

2. The product of thermochemical activation (TCA) of hydrargillite; phase composition: amorphous product with an admixture of boehmite (1 ÷ 2 wt.%); particle size 0-50 microns; loss on ignition (IFR) 11.5 wt.%.

3. The product of mechanochemical activation (MCA) of hydrargillite; phase composition: amorphous product with an admixture of boehmite (3 ÷ 4 wt.%); particle size 0-20 microns; loss on ignition (IFR) 13.6 wt.%.

4. Nitric acid.

5. Ammonia water.

6. Water chemically purified (HOV).

Equipment.

1. An autoclave with a capacity of 100 m ³ at a maximum pressure of 10 ati (180-200 ° C).

2. An autoclave with a capacity of 5 l at a maximum pressure of 10 ati (180-200 ° C).

3. Filter press (FP) with a volume of 7 m ³ with a lavsan fabric that traps particles larger than 5 microns.

4. Spray dryer (PC) with a capacity of up to 2 m ³ / h on evaporated moisture.

5. Belt calcining furnace.

6. Tanks with mixers of various volumes.

Description of the technology.

I. Flushing - 1 product of TXA / MXA of hydrargillite from sodium oxide.

Example I.1.

60 m ^{3 of} HOV with a pH of 6.62 at a temperature of 25 ° C were poured into a container with a mixer of 100 m ³ volume and 3550 kg of TXA product were loaded with constant stirring for 0.5 hour; the suspension has a pH of 9.2. Poured 22 l of nitric acid to pH 7, stirring for 1 hour. Suspension at pH 7.54 is applied to the filter press. The AF washes were carried out in three steps with an intermediate discharge of the circulating filtrate, which had a pH of 8.14; pH 8.25 and pH 8.52; the total consumption of HOV was 104 m ³ or 29 m ³ / t Al ₂ O ₃ , the washing time was 8 hours.

To determine the residual sodium oxide, samples were taken from the upper, middle, and lower parts of the AF frame; the residual content of sodium oxide was 0.074%; 0.068%; 0.062 wt.%, Respectively.

The phase composition of the precipitate after 96 hours of storage:

Bayerite 90 wt.%, Gibbsite 10 wt.%.

Example I.2

40 m ^{3 of} HOV were poured into the container according to Example I.1 at a temperature of 50-60 ° C and 14100 kg of TXA product were loaded with constant stirring and circulation of the suspension; pH 9.6. Poured 37 l of nitric acid with constant stirring to pH 7 for 15 hours; while the temperature of the suspension rose to 90 ° C; 40 m ^{3 of} cold HOV was added to the tank, which reduced the temperature to 60-70 ° C. The suspension has a pH of 7.73. Water consumption 5.7 m ³ Al ₂ O ₃ .

At this stage of washing, the content of sodium oxide in the precipitate was 0.09%. The phase composition of the precipitate after 72 hours of storage is 90 wt.% Bayerite, the rest is an amorphous product.

Example I.2.1.

Further washing was continued on a filter press, the temperature of the washing water was 58 ° C, at a pH of 7.0-7.35. Rinsing was carried out on two clogs of the filter press in two steps on each clog with an intermediate discharge of the circulating filtrate. The water consumption at this stage was 11.2 m ³ / t Al ₂ O ₃ for the first FP block, the content of sodium oxide in the sediment was 0.022 wt.%; for the second driving, the water consumption was 9.2 m ³ / t Al ₂ O ₃ , the washing time was 10 hours, and the content of sodium oxide was 0.028 wt.%. The phase composition of the precipitate after 96 hours of storage: bayerite 90 wt.%, The rest is an amorphous product.

Example I.2.2.

A suspension with a sodium oxide content of 0.09 wt.% According to Example I.2 was applied to a filter press, where it was washed in two steps with an intermediate filtrate discharge at a temperature of 40 ° C for 3 hours. The water consumption was 13.5 m ³ / t Al ₂ O ₃ ; the content of sodium oxide is 0.024 wt.%. The phase composition of the precipitate: 90 wt.% Bayerite, the rest is an amorphous product.

Tables 1 and 2 give examples of other conditions and the results of washing products of TXA / MXA and subsequent washing in a filter press. As follows from the above materials, the proposed method of washing the product TXA / MXA can reduce the content of sodium oxide to 0.003 wt.% And to regulate it over a wide range; while the duration of the process is reduced from 7 to 10 times, and there are practically no losses.

table 2 Flushing conditions on the filter press №№ Raw materials Water consumption, m ³ / t Al ₂ O ₃ Circulation number T, ° С pH Duration, hour The content in the paste Na ₂ O, wt.% I.3.1 from I.3 10.3 3 56 7.0 ÷ 7.2 3.0 0,03 I.3.2 from I.3 5,6 3 56 6.8 ÷ 7.1 3.0 0,045 I.4.1 from I.4 4.9 2 62 6.1 ÷ 7.0 4,5 0,07 I.4.2 from I.4 15.8 3 50 ÷ 60 5.8 ÷ 6.3 4.0 0.003 I.6 from I.5 10,2 3 58 6.8 ÷ 7.8 4.0 0.20

From a consideration of the washing results of the TXA / MXA product, it follows that under conditions of its treatment with water at a pH of 7.54-9.2 and a temperature below 90 ° C, along with the removal of sodium oxide, a phase transformation of amorphized hydrargillite → bayerite occurs.

II. Plasticization.

Taking into account the above materials, the raw material of the plasticization process (treatment in an aqueous medium at pH 2 ÷ 3 and a temperature of 140-160 ° C) is either the initial product TXA / MXA hydrargillite with an initial content of sodium oxide of 0.48 wt.% (Main route), or washed product TXA / MXA with a low content of sodium oxide having a phase composition: bayerite up to 90% wt. + TXA / MHA amorphized product (routes for amorphized and pure products).

The main route in the process of plasticization process

amorphized product TXA / MXA hydrargillite → boehmite.

Processes occur in the route for pure and ultra-pure products

bayerite → boehmite → hydrargillite.

The processes take place over time, so the phase composition of the products depends on the processing time.

Example II.1

In an autoclave with a useful volume of 27 m ^3, 3084 kg of the initial product of TXA hydrargillite were loaded, filled with HOB water to a volume of 21 m ³ (80% of the useful volume), nitric acid was added with stirring in an amount of 0.1 mol of HNO ₃ per mol of Al ₂ O ₃ .

The ratio of solid: liquid is 1: 7, pH 4.1.

In the autoclaving process, product samples were taken and their phase composition was analyzed on an X-ray diffractometer.

Duration, hour Phase composition, wt.% 5 Boehmite 80; gibbsit 20 10 Boehmite 82; gibbsit 18 13 Boehmite 90; gibbsit <10 traces of γ-Al ₂ O ₃

In the final product, pH is 3.57.

Example II.2

In the autoclave according to example II.1, 2989 kg of the TXA product of hydrargillite, pre-washed by decantation to a content of sodium oxide of 0.38 wt.%, Filled with HOB water to 21 m ³ , were added and with constant stirring nitric acid in an amount of 0.15 mol per mol of Al ₂ O ₃ .

The ratio of solid: liquid is 1: 7, pH 3.6.

Duration, hour Phase composition, wt.% 5 Boehmite 60; Gibbsit 10-20; traces of γ-Al ₂ O ₃ 10 Boehmite 80; gibbsite 10-20; traces of γ-Al ₂ O ₃ 12 Boehmite 85; Gibbsite 10; traces of γ-Al ₂ O ₃

Example II.3.

In the autoclave according to Example II.1, 2773 kg of TXA product, hydrargillite, washed in a filter press under the conditions of Example I.4.1, were loaded to an Na ₂ O content of 0.07% wt., Phase composition: bayerite 100%.

With constant stirring, nitric acid was added at a molar ratio of 0.2 mol / mol Al ₂ O ₃ , to a pH of 2.42, with a solid: liquid ratio of 1: 7.5.

Duration, hour Phase composition, wt.% 5 Bayerite> 90 10 Bayerite 80; boehmite 20 fifteen Bayerite 60; boehmite 30; admixture of γ-Al ₂ O ₃ and gibbsite 19 Bayerite 20; boehmite 60; gibbsit 20.

III. Flushing-2 product of plasticization.

Example III one.

In a container with a stirrer with a volume of 50 m ^3, 10 m ^{3 of} HOV is filled, with constant stirring, the plasticization product of Example II is loaded. 1 (for 13 hours) in an amount of 20 m ³ , ammonia water was poured to a pH of 8.0, HOV was added to a volume of 45 m ³ , stirring 0.5 hour; the suspension was applied to a filter press, where the washing was carried out with water at a temperature of 56 ° C, the consumption of HOW was 10.3 m ³ / t Al ₂ O ₃ , the washing time was 17 hours, the content of sodium oxide was 0.08 wt.%, phase composition: boehmite ~ 100 wt.%.

Table 3 below shows other conditions and results of washing-2 of the plasticization product.

Table 3 №№ suspension pH HOV consumption, m ³ / t Al ₂ O ₃ Duration of washing, hour The content of sodium oxide,% wt. III.2 7.5 16.1 28.0 0.12 III.3 8.6 9,4 14.0 0.06 III.4 9.7 8.9 10.5 0.04

From the results of Table 3 it follows that at pH 7.5 of the suspension, the washing time increases sharply while reducing efficiency; pH increase is limited by safe working conditions.

IV. Spray drying.

Example IV.1.

The product of activation of hydrargillite after washing-1 according to Example I.1 is loaded into a container with a mixer of 100 m ³ volume, added HOV to a volume of 85 m ³ , stirring for 1 hour, the ratio in suspension is solid: liquid 1: 8.5. The suspension was applied to spray drying at a temperature in the chamber of 170-200 ° С, a powder with a particle size (after calcination at 550 ° С) of 0-60 μm was obtained, phase composition of the powder: bayerite> 90 wt.%.

Table 4 below shows other conditions and spray drying of a suspension of the hydrargillite activation product after washing-1.

Table 4 No. n / a example Solid to Liquid Ratio Particle size, microns The phase composition,% wt. IV.1.1 1: 8 0-60 Bayerite> 90 IV.1.2 1: 9 0-50 Bayerite> 90 IV.1.3 1:10 0-40 Bayerite> 80 Boehmite 10 ÷ 20 IV.1.4 1: 11.5 0-25 Bayerite> 60 Boehmite 30 IV.1.5 1: 7.5 0-120

With increasing ratio of solid: liquid in the sprayed suspension of the washed activation product to 1: 7.5, the particle size of the powder significantly exceeds the required size (up to 40 ÷ 60 μm), and when diluted above 1:10 (up to 1: 11.5), the phase composition of the material.

Example IV.2

The plasticization product of TCA hydrargillite according to example II.1 (13 hours) was loaded into a container with a stirrer of 100 m ³ volume, HOV was added to a volume of 80 m ³ , stirring 0.5 hour, solid: liquid ratio in suspension 1: 8; the suspension was applied for spray drying at a temperature in the chamber of 180-210 ° C, a powder with a particle size (after calcination at 550 ° C) of 0-60 μm was obtained, the phase composition of the powder: boehmite> 90 wt.%, gibsite 10 wt.% .

Table 4a below shows other conditions and spray drying of the plasticization product suspension before and after washing-2.

Table 4a No. n / a example Solid to Liquid Ratio Particle size, microns The phase composition,% wt. IV.2.1 Example II.1 in 13 hours 1: 8 0-100 Boehmite 90 IV.2.2 Example II.1 in 13 hours 1: 9 0-40 Boehmite 90 IV.2.3 Example II.3 in 5 hours 1:10 0-25 Bayerite 90 IV.2.4 Example II.3 in 5 hours 1: 11.5 0-18 Bayerite 50 Aluminum oxide else

With an increase in the ratio of solid: liquid in the sprayed suspension of the product to 1: 7, the particle size of the powder significantly exceeds the required size (up to 50 ÷ 60 μm), and when diluted above 1:10 (up to 1: 11.3), the phase composition of the powder changes

V. Annealing.

Example V.1.

The product of the MHA of hydraragillite in an amount of 1200 kg was calcined at a temperature of 450 ° C for 5 hours in the conditions of a belt furnace; the product obtained was an amorphized aluminum oxide powder with a particle size of less than 20 microns.

Example V.2.

The powder obtained by spray drying according to example IV.1, is calcined at a temperature of 550 ° C for 5 hours in a belt oven, an aluminum oxide powder is obtained in the form of a modification of η-Al ₂ O ₃ with a particle size of less than 60 μm.

Example V.3.

The powder obtained by spray drying according to example IV.2, is calcined at a temperature of 650 ° C for 6.5 hours in a belt oven, an aluminum oxide powder is obtained in the form of a modification of γ-Al ₂ O ₃ with a particle size of less than 60 μm.

At annealing temperature below 450 ° С, the initial hydroxide phase is present in the calcination products; at a temperature above 650 ° С, the particle size of the powder increases due to sintering.

VI. Obtaining powders of hydroxide and alumina.

Example VI.1.

Obtaining boehmite structure aluminum hydroxide powder (main route)

The product TXA hydrargillite is plasticized according to the conditions of example II.1. after 13 hours, an aluminum hydroxide paste with a phase composition is obtained: boehmite 90%, gibbsite <10%, traces of γ-Al ₂ O ₃ , sodium oxide content of 0.48 wt.%. The resulting aluminum hydroxide boehmite structure is loaded into a container with a stirrer with a volume of 100 m ³ ; according to the conditions of example IV.2 prepare an aqueous suspension and served on spray drying at a temperature in the chamber 180-210 ° C. A powder with a phase composition was obtained: boehmite> 90 wt.%, Gibbsite <10 wt.%; the content of sodium oxide of 0.48 wt.%; particle size (after calcination at a temperature of 550 ° C) 0-60 microns (mainly 30-50 microns).

Example VI.2.

Obtaining powder of aluminum hydroxide bayerite structure (route for pure products)

Washed according to the conditions of example I.1. product TXA hydrargillite with a residual content of sodium oxide of 0.071 wt.% loaded into a container with a stirrer with a volume of 100 m ³ ; a suspension is prepared according to the conditions of example IV.1 with a ratio of solid: liquid = 1: 8.5 and is applied for spray drying at a temperature in the chamber of 170 ÷ 200 ° C; a powder with a phase composition was obtained: bayerite> 90 wt.%. The particle size determined after calcination at a temperature of 550 ° C was 0-60 μm (mainly 30 ÷ 50 μm), the content of sodium oxide was 0.070 wt.%.

Example VI.3.

Obtaining boehmite structure aluminum hydroxide powder (route for pure and ultrapure products).

The product TXA / MXA of hydrargillite is washed under the conditions of examples 1.2, 1.2.2; a precipitate was obtained with a phase composition: 90 wt.% bayerite, the rest is an amorphous product; the content of sodium oxide is 0.024 wt.%. The precipitate is loaded into an autoclave with a useful volume of 27 m ³ and plasticization is carried out according to the conditions of example II.1. After 14 hours, a product with a boehmite phase composition of ≥90% was obtained. The plasticization product is loaded into a container with a stirrer and washed in the conditions of example III.1. The obtained washing product-2 with a content of sodium oxide of 0.003 wt.%; phase composition: boehmite ~ 100%. The spray drying of the product was carried out under the conditions of example IV.1. A powder with a particle size (after calcination at a temperature of 550 ° C) of 0-60 μm (mainly 30 ÷ 50 μm) was obtained; phase composition of the powder: boehmite ~ 100%, sodium oxide content of 0.003 wt.%.

Example VI.4.

Obtaining powders of aluminum oxide:

- amorphized Al ₂ O _{3 is} obtained by calcining the product TXA / MXA hydrargillite at a temperature of 450-550 ° C.

- alumina in the modification of γ-Al ₂ O _{3 is} obtained by calcining at a temperature of 550-600 ° C powders of aluminum hydroxide predominantly boehmite structure according to examples IV.2.1, IV.2.2, VI.1, VI.3 and others;

- alumina in the modification of η-Al ₂ O ₃ by calcining at a temperature of 550-650 ° C powders mainly bayerite structure according to examples IV.1.2, IV.1.3, VI.2 and others;

- alumina, which is a mixture of γ-Al ₂ O ₃ + η-Al ₂ O ₃ + Al ₂ O ₃ amorphized, is obtained by calcining at a temperature of 450-650 ° C powders of aluminum hydroxides consisting of a mixture of hydroxides of boehmite structure and bayerite structure and residual product TXA / MHA.

The ratio of aluminum oxides in the calcination product is close to the ratio of their precursors in the hydroxide mixture.

Analysis of the above materials allows us to conclude that the proposed technical solution makes it possible to obtain a wide range of powdered hydroxides and aluminum oxides - components of catalysts and adsorbents for large-scale processes of oil refining and petrochemicals.

Claims (5)

1. A method of producing aluminum hydroxide powder, including thermochemical and / or mechanochemical activation of hydrargillite, characterized in that the activation products are washed on a filter press at a pH of less than 9, then water is added to the washed activation product to a solid: liquid ratio of 1 :( 8-10), and the resulting suspension is subjected to spray drying at 170-200 ° C. 2. A method of producing aluminum hydroxide powder, including thermochemical and / or mechanochemical activation of hydrargillite, characterized in that the activation product is plasticized at a pH of 2-3 and a temperature of 140-160 ° C, then water is added to the plasticization product to a ratio of solid suspension: liquid, equal to 1: (7.5-15), and the suspension is fed to spray drying at a temperature of 180-210 ° C. 3. The method according to claim 2, characterized in that the activation product is washed in a filter press at a pH of less than 9. 4. The method according to claim 2, characterized in that the plasticization product is washed on a filter press at a pH of more than 7.5. 5. A method of producing aluminum oxide, comprising calcining an aluminum hydroxide powder obtained according to any one of claims 1 to 4, at a temperature of 450-650 ° C.

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