CN1715193A

CN1715193A - New process for preparing high quality Co3O4

Info

Publication number: CN1715193A
Application number: CN 200410023350
Authority: CN
Inventors: 胡国荣
Original assignee: HUNAN RESHINE NEW MATERIAL CO Ltd
Current assignee: Nantong Reshine New Material Co., Ltd.
Priority date: 2004-06-28
Filing date: 2004-06-28
Publication date: 2006-01-04
Anticipated expiration: 2024-06-28
Also published as: CN100398454C

Abstract

In the new process of preparing high quality Co3O4 product, Co salt with crystalline water is loaded into corundum crucible or other special container at normal pressure, roasted at 250-900 deg.c in special reaction furnace for 5-20 hr for growing complete crystal grain, and finally cooled naturally, so as to obtain Co3O4 powder in single polygonal cube structure and with complete crystal form and high density. The production process is environment friendly, short in time, low in cost, high in yield and high in product quality.

Description

Novel method for preparing high-quality cobaltosic oxide

Technical Field

The invention relates to a manufacturing technology of metal oxide, in particular to a method for preparing high-quality cobaltosic oxide by directly roasting cobalt hydrate salt in one step.

Background

The wide application of the new energy secondary lithium ion technology promotes the rapid expansion of the preparation technology and the production scale of the lithium cobaltate material which is used as the anode material of the lithium ion battery in China, particularly the lithium cobaltate material taking battery-grade cobaltosic oxide as the main rawmaterial. As a preferred raw material of the anode material, the preparation technology of battery-grade cobaltosic oxide also becomes one of the key problems of the preparation technology of the anode material. At present, there are two main approaches for preparing cobaltosic oxide, one is spray roasting (including Umicore company in Belgium) by using a cobalt salt solution, which has the advantages of simple process, easy control and stable product quality, but the method has very large equipment investment, about 1000-2000 ten thousand dollars are needed, and energy consumption caused by preparing a roasting solution is very large, which is difficult to realize in China, and anions in the roasted cobaltosic oxide powder are difficult to clean. Secondly, cobalt salt is pre-precipitated into hydroxide of cobalt, and then the precipitate is thermally decomposed to produce cobaltosic oxide (beginning with the American OMG company), so that the method has the advantages of less equipment investment compared with the prior method, and good control on the appearance and the granularity of the product, but the method has the defects of long flow, unstable precipitate phase state, difficult washing of impurity ions such as sodium in the precipitate, easy bringing of other impurities such as iron, calcium, magnesium and the like in the precipitation process, and pollution of the produced mother liquor to the environment caused by a large amount of ammonium salt and chloride ions; at present, most of the domestic methods adopt cobalt chloride solution to precipitate cobalt salt (represented by cobalt tungsten limited, Jinchuan and Ganxianzhou) by using precipitator such as ammonium bicarbonate or ammonium oxalate and the like to generate precipitates such as cobalt carbonate or cobalt oxalate and the like, and then thermally decompose the precipitates such as cobalt carbonate, cobalt oxalate and the like to prepare cobaltosic oxide powder. The preparation of the lithium ion battery anode material lithium cobaltate putsstrict requirements on the raw material cobaltosic oxide, and mainly comprises the following steps: the granularity requirement is small and the distribution is uniform; the shape is single and is a polyhedral cubic structure; the surface activity is high; the tap density is high, and the impurity content of the product is low; the raw materials are easily available and cheap. The cobaltosic oxide prepared by the traditional method is mainly used in the field of hard alloy and ceramics, has the defects of amorphous shape, wide particle size distribution, low tap density, poor surface activity and the like, and is difficult to meet the preparation requirement of the anode material lithium cobaltate for the lithium ion secondary battery.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method solves the problems of large equipment investment, long flow, high energy consumption, serious environmental pollution, high cost, unstable production, difficult control of product appearance and granularity, incapability of meeting the requirement of manufacturing lithium cobaltate and the like in the traditional process of preparing the cobaltosic oxide by using a spray roasting and precipitation-sintering method; the novel method for preparing the high-quality cobaltosic oxide has the advantages of advanced process, stable production, no sewage discharge, capability of absorbing a small amount of generated acid gas into a byproduct, environmental protection, low equipment investment, low production cost, short flow, low energy consumption, good product quality and high yield.

The technical scheme adopted by the invention is as follows: cobalt salt with crystal water is loaded into a special reaction furnace by a special container under normal pressure, and high-quality cobaltosic oxide powder is prepared by sintering.

In the technical scheme, the cobalt salt with the crystal water is adopted as CoCl₂·xH₂O，Co(NO₃)₂·xH₂O，CoSO₄·xH₂O，Co(AC)₂·xH₂O, (x) is 1 to 6.

In the above technical scheme, the special container can adopt a corundum crucible or a ceramic crucible or a graphite crucible or a clay crucible.

In the technical scheme, the special reaction furnace is an improvement of the existing electric heating kiln and comprises a calcining part and a tail gas treatment and recovery part, a furnace body of the calcining part is made of refractory materials built in the outer wall of an iron shell, an electric heating device is installed at the lower part and the side part in the furnace body, the electric heating device is separated from a hearth by a refractory baffle, a vertical air channel and a gas buffer chamber are arranged at the upper part of the middle section of the furnace body, the upper part of the hearth is communicated with the gas buffer chamber through the vertical air channel, a flue gas outlet of the gas buffer chamber is connected with the tail gas treatment and recovery part, the furnace body is internally divided into a preheating zone, an evaporation zone, a reaction decomposition zone and a cooling zone, an air wall is arranged at a furnace mouth, a push plate is further installed in the furnace body, raw materials are pushed into the reaction furnace by the push plate to be calcined to prepare high-, The absorption tower is a spraying absorption tower and is also connected with a circulating device and a recovery device which are formed by connecting and communicating a recovery tank, a circulating pump and a circulating pipeline.

In the technical scheme, the temperature rise speed of the special reaction furnace is 2-10 ℃/min, the temperature inthe furnace is 250-900 ℃, and the sintering time of the cobalt salt with the crystallization water in the special reaction furnace is 5-20 hours.

The invention provides a preparation process for sintering and decomposing cobalt salt as a precursor directly entering a specially designed reaction furnace, which can replace the existing spray roasting and precipitation-sintering process to produce cobaltosic oxide by adopting the process for preparing cobaltosic oxide, inherits the advantages of the spray roasting process, completely does not undergo the wet precipitation part of the traditional process in the process flow, thereby having stable production, simultaneously having no sewage discharge, only generating a small amount of acid gas which is completely absorbed by the special treatment of the invention and can be sold as a byproduct, greatly improving the environment, having less equipment investment and being far lower than the equipment investment of spray roasting equipment and precipitation-sintering process, greatly reducing the production cost, simplifying the process control of production and the maintenance of equipment, and greatly improving the production efficiency, the method realizes the aims of short production process, low energy consumption, no pollution, high yield, low cost and the like. In particular, the prepared cobaltosic oxide has good quality, reasonable granularity, single appearance and large tap density, and is high-quality battery grade cobaltosic oxide. The particle size is 3-8 μm, the appearance is single and the crystal structure is polyhedral, the crystal structure is complete, no impurity phase appears on the powder X-ray diffraction pattern, and the tap density is 2.2-2.8g/cm³Can completely meet the requirement of preparing the anode material lithium cobaltate for the lithium ion secondary battery.

Drawings

FIG. 1 is an SEM image of cobaltosic oxide prepared by the invention

FIG. 2 is an XRD pattern of cobaltosic oxide prepared by the present invention

FIG. 3 is a schematic view of a longitudinal structure of a dedicated reaction furnace

FIG. 4 is a sectional view taken along line A-A in FIG. 3

FIG. 5 is a sectional view taken along line B-B in FIG. 3

FIG. 6 is a cross-sectional view taken along line C-C in FIG. 3

Detailed Description

The new method for preparing high-quality cobaltosic oxide provided by the invention is a hydrated cobalt salt one-step direct roasting method, namely cobaltosic oxide powder completely meeting the requirement of preparing lithium cobaltite can be directly obtained by starting from raw materials and only needing one roasting process.

The invention uses cobalt salts with water of crystallization, e.g. CoCl₂·xH₂O，Co(NO₃)₂·xH₂O，CoSO₄·xH₂O，Co(AC)₂·xH₂O, (x ═ 1 to 6), and the like, with CoCl being particularly preferably used₂·xH₂O, a special container such as a corundum crucible or a ceramic crucible or a graphite crucible or a clay crucible is used for containing materials under normal pressure, the thickness of the materials is 2-5cm, the materials are loaded into a special reaction furnace which is designed by special improvement, the special reaction furnace is at least one improvement of a tunnel kiln, a pushed slab kiln, a rotary kiln and a box furnace, the temperature is increased to 250-900 ℃ at the temperature rising speed of 2-10℃/min, particularly 500-850 ℃ is preferred, cobalt salt is rapidly decomposed to obtain particles with uniform particle size distribution, the particle crystal form is further promoted to completely grow by keeping a certain sintering time for 5-20 hours, particularly 15-20 hours is preferred, and finally the product is naturally cooled and collected to obtain the particles with the particle size of 3-8 mu m and single appearance and a polyhedral structure, as shown in figure 1, the crystal form has complete structure, no impurity phase appears on powder X-ray diffraction diagram, as shown in figure 2, the tap density is 2.2-2.8g/cm³The cobaltosic oxide powder. Acid gas generated in the process is introduced into a condenser through a draught fan of a tail gas treatment and recovery part in the special reaction furnaceAnd (4) cooling, circularly absorbing by an absorption tower, and taking the product as a byproduct after complete absorption.

Referring to fig. 3 and 4, the special reaction furnace of the present invention is an improvement of the existing electric heating furnace, such as a pusher kiln, a box furnace, a tunnel kiln, a rotary kiln, etc., and comprises a calcination part and a tail gas treatment and recovery part, wherein a furnace body 1 of the calcination part is formed by building refractory materials 3 in an iron shell outer wall 2, the refractory materials 3 are heat preservation layers, mullite fiber or high alumina fiber, light corundum mullite, ceramic fiber, low iron alumina poly light high alumina brick, heavy corundum mullite, silicon carbide, etc. can be adopted as the refractory materials, electric heating devices are installed at the lower part and the side part in the furnace body, the upper heating mode of the traditional furnace is cancelled, the electric heating devices are resistance wires 4 and electric heating silicon carbon rods 5, the electric heating devices are separated from a hearth by refractory brickbaffle 6, so as to strengthen the protection of the heating elements, a vertical air duct 7 and a gas buffer chamber 8 are arranged at the upper part of the middle section of the furnace body, the upper part of the hearth is communicated with a gas buffer chamber 8 through a vertical air duct 7, a flue gas outlet 9 of the gas buffer chamber 8 is connected and communicated with a tail gas treatment and recovery part, the inside of the furnace body 1 is divided into a preheating zone 10, an evaporation zone 11, a reaction decomposition zone 12 and a cooling zone 13, two to three gas walls are arranged at a furnace mouth 14 and are arranged in a 90-degree crossed manner, and the gas walls are formed by air nozzle injection. The furnace body 1 is also provided with a push plate 15 which is mechanically pushed or hydraulically and mechanically driven. The cobalt salt raw material with the crystal water is pushed into the reaction furnace by a push plate 15, and is preheated for 2-3 hours in a preheating zone firstly, and part of the crystal water is removed:

then entering an evaporation zone for 3-5 hours, and removing part of crystal water:

the dehydrated crystal water enters a gas buffer chamber 8 from a vertical air duct 7 in the form of water vapor and finally enters a tail gas treatment and recovery part, and a cobalt salt raw material enters a reaction and decomposition zone for 4-6 hours to generate violent reaction to generate cobaltosic oxide and acid gas: acid gas also enters a gas buffer chamber 8 from a vertical air duct 7, the cobaltosic oxide particle crystal form further grows completely, and finally enters a cooling zone in the furnace body for about 4-6 hours, and is naturally cooled and collected to finally obtain the cobaltosic oxide particle crystal formHigh-quality battery-grade cobaltosic oxide powder. The aforementioned water vapor and acid gas are passed through a pipe by a draft fan 16Introducing the acid gas into a condenser 17 for cooling and pre-recycling, wherein the condenser 17 is made of graphite or titanium steel and is connected with a cooling water inlet 18 and a cooling water outlet 19, introducing the residual gas after passing through the condenser into a spray absorption tower 20 for cyclic absorption until the residual gas is completely absorbed, leading out and emptying the residual gas by a draught fan 24 and a pipeline, matching with the spray absorption tower 20, installing a recycling tank 21 and a circulating pump 22, and recycling and absorbing the mother liquor and outputting the mother liquor by a pipeline 23.

The method for preparing the battery grade high-quality cobaltosic oxide powder by directly roasting the hydrated cobalt salt in one step, which is provided by the invention, omits a wet cobalt precipitation part and a crushing and grading process after sintering in the traditional process while improving the product quality, simplifies the process flow, greatly saves the production equipment investment, simplifies the production process control and equipment maintenance, greatly improves the yield and protects the environment.

The condenser, the spray absorption tower, the recovery tank, the circulating pump and the induced draft fan can adopt the existing environment-friendly equipment.

Examples

Cobalt salt CoCl containing crystal water₂·xH₂O or Co (NO)₃)₂·xH₂O or CoSO₄·xH₂O or Co (AC)₂·xH₂O, (x is 1-6) is filled in a corundum crucible, pushed into a special reaction furnace of the invention, heated to 850 ℃ at a heating rate of 5 ℃/min and calcined for 15 hours to ensure that the crystal form of the particles further grows completely, and finally, the particles are naturally cooled and collected to obtain powder with the average particle size of 3-8 mu m and the tap density of 2.2-2.8g/cm³The phase analysis of ray diffraction shows that the powder is pure phase Co₃O₄(ii) a The gas generated in roasting is firstly introduced into a condenser by a draught fan for cooling and pre-collecting, and then is introduced into a special absorption device for completely absorbing to prepare acid as a byproduct, and the obtained powder can completely meet the requirement of preparing the anode material lithium cobaltate for the lithium ion secondary battery.

Claims

1. A process for preparing high-quality cobaltosic oxide includes such steps as loading the cobalt salt with crystal water in a special container, loading it in a special reactor, and sintering.

2. The method of claim 1, wherein the cobalt salt with crystal water is CoCl₂·xH₂O，Co(NO₃)₂·xH₂O，CoSO₄·xH₂O，Co(AC)₂·xH₂O, (x) is 1 to 6.

3. The method for preparing high-quality cobaltosic oxide according to claim 1, wherein said special container can be corundum crucible or ceramic crucible or graphite crucible or clay crucible.

4. The special reaction furnace for preparing the high-quality cobaltosic oxide according to claim 1, which is characterized by comprising a calcining part and a tail gas treatment and recovery part, wherein a furnace body of the calcining part is made of refractory materials built in the outer wall of an iron shell, an electric heating device is arranged at the lower part and the side part in the furnace body, the electric heating device is separated from a hearth by a refractory baffle plate, a vertical air duct and a gas buffer chamber are arranged at the upper part of the middle section of the furnace body, the upper part of the hearth is communicated with the gas buffer chamber through the vertical air duct, a flue gas outlet of the gas buffer chamber is connected with the tail gas treatment and recovery part, the furnace body is divided into four parts, namely a preheating zone, an evaporation zone, a reaction decomposition zone and a cooling zone, a gas wall is; the tail gas treatment and recovery part comprises a draught fan, a condenser and an absorption tower which are sequentially connected through pipelines, the condenser is also provided with a condensate water inlet and a condensate water outlet, the absorption tower is a spray absorption tower, and a circulating device and a recovery device which are formed by connecting and communicating a recovery tank, a circulating pump and a circulating pipeline are also connected and installed.

5. The method of claim 1, wherein the heating rate of the reaction furnace is 2-10 ℃/min, the temperature in the reaction furnace is 250-900 ℃, and the sintering time of the cobalt salt with crystal water in the reaction furnace is 5-20 hours.