RU2365650C1 - Method of preparation of slag-soda charge containing vanadium for oxidising roasting and processing line for this process - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the method and device of preparation slag-soda charge containing vanadium for oxidising roasting. The method involves crushing the slag, magnetic separation, breaking, mixing it with chemical additives for the follow-up roasting. Before roasting the resulting mixture is granulated, and the slag is crushed in several steps classifying the slag into size groups. The first step is preparatory when the slag is crushed into pieces of 200 mm maximum. The second step is when the slag is crushed into pieces of 80 mm maximum, and the slag is classified into the following fractions: +80 mm, 10-80 mm and - 10 mm. During the third step the resulting fraction of 10-80 mm is crushed on the rotary crusher in the closed cycle with the vibration onesieve sizing screen with the sieve cells of 10×10 mm. Then the fraction of 10 mm is mixed with the early obtained fraction of 10 mm and processed in two steps. Step 1 does centrifugal crushing and seperation to achieve pieces of 0.15 mm that go through the centrifugal crushing and air centrifugal separation in Step 2. The slag with 0.06-0.15 mm pieces is supplied to the dosing and mixing unit to determine the content of vanadium pentoxide in the slag depending on which the required amount of chemical additives and soda is supplied to be mixed with the slag.

EFFECT: reduced loss of vanadium in the course of preparing the charge, reduced content of the metallic inclusions, increased total extraction of vanadium, increased output of vanadium products, better environment.

7 cl, 1 dwg

Description

Technical field

The invention relates to the field of ferrous metallurgy, and in particular to a method for preparing a mixture for producing vanadium-containing products.

State of the art

The main material for the production of vanadium pentoxide according to the pyrometallurgical scheme adopted in Russia for processing vanadium-containing raw materials is vanadium-containing slag - a product of processing in converters of vanadium-containing cast iron.

Slag consists of an oxide part (Fe, V, Cr oxides, etc.) and inclusions of the metal phase from coarse shard (over 200 mm) to a fine fraction of less than 0.5 mm. The content of metal inclusions is 20-30%. Vanadium slag contains up to 40% of iron oxides with weakly magnetic properties, which complicates the magnetic separation of iron and increases the loss of slag from the metal screening.

Due to the high content of SiO ₂ , Al ₂ O ₃ , MgO, TiO _2, and other oxides, converter slag is a highly abrasive material.

The converter slag used must comply with the requirements established in STP 115-7-2005 “Vanadium Converter Slag”.

A known method of preparing vanadium-containing slag for oxidative calcination using a reagent additive, including crushing slag, wet grinding, classification by size, metal separation by screening and magnetic separation. To increase the degree of vanadium recovery, the reagent additive is introduced after filtration, and the resulting mixture is subjected to additional joint grinding (AS USSR No. 947214, IPC C22B 34/22, BI No. 28, 1982). However, in the known method, the principle of wet grinding is used.

The closest in technical essence and the achieved result to the proposed technical solution is the method and processing line for the processing of vanadium slag (A.A. Karpov et al. “Prospects for the development of process control systems of the ferroalloy shop of ChMZ OJSC”, Metallurg, No. 8, 2000, p. 48-50). The prototype method of preparing a vanadium-containing slag-batch mixture for oxidative firing includes crushing slag, magnetic separation, grinding, mixing it with chemical additives for subsequent firing.

The line for the preparation of a vanadium-containing slag soda mixture for oxidative firing contains:

Jaw crusher hopper, jaw crusher, slag storage hopper, deck storage, crushing slag decks, ball mill hopper, ball mill, elevator, electromagnetic separator, metal screening, tube mill hopper, automatic slag dispenser, tube mill, soda hopper with soda hopper secondary magnetic separation separator, conveyor for feeding the mixture into the calcining furnace, the calcining furnace.

At Chusovskaya Metallurgical Plant OJSC, the charge preparation complex includes:

- a slag warehouse equipped with a bridge magnetoelectric crane for unloading decks of vanadium slag, crushing them with a stove and a coper ball, jaw crushers and a conveyor system designed to supply crushed slag;

- a charge warehouse, on which there are bunkers for storing crushed slag, belt conveyors for slag, bunker and bunker for receiving, storing and feeding soda to production, a unit for fractional separation of captured metal inclusions;

- a batch preparation section, comprising 4 ball mills ⌀2.7 × 1.45 m and 2 tubular mills ⌀1.5 × 5.6 m for dry slag grinding, conveyors, elevators, feeders for feeding slag, soda, magnetic separators for separating metal inclusions.

The disadvantages of the existing scheme of charge preparation are:

- The existing technological scheme for processing vanadium-containing slag and outdated equipment do not allow expanding the range of products, do not meet the needs of the customer as supplied vanadium pentoxide.

- There is no possibility of operational regulation of the degree of grinding of the charge, which leads to heterogeneity in fractional composition and a significant over-grinding of the charge.

- There are quite large losses of vanadium with detachable metal screening due to:

- the use of crushing and grinding equipment that does not allow to effectively separate the metal and slag phases;

- application for the extraction of metal inclusions of magnetic separators that do not correspond in their parameters and installation method to the characteristics of the material to be enriched and the features of the process.

- Due to the unsatisfactory separation of metal inclusions from the finished charge, at least 2% of the recovered metal screen is lost in the kiln due to the formation of iron vanadates and a decrease in the yield of soluble vanadium compounds.

- Losses of vanadium with pyleunosom behind roasting furnaces reach 2%. Both rotary kilns operate on natural draft without gas cleaning equipment. There is no system for feeding into the production of trapped dust and waste leaching waste, which also reduces the overall extraction of vanadium in general in the chemical section.

- Aspiration systems of grinding equipment are not able to provide modern requirements for the air of the working area in the premises of the department.

- Currently, the areas of charge preparation and firing are one of the main sources of air pollution in the plant.

Disclosure of invention

The objective of the invention is to develop a simple and effective method of preparing the mixture for oxidative firing, free from the disadvantages of the prototype, and the creation of a high-performance production line for its implementation.

The problem is solved using the features specified in the 1st claim that are common with the prototype, such as a method of preparing a vanadium-containing slag-batch mixture for oxidative firing, including crushing slag, magnetic separation, grinding, mixing it with chemical additives for subsequent firing, and distinctive essential features, such as before firing the resulting mixture is granulated, and crushing is carried out in several stages with classification by size, in the 1st preparatory stage, crushed into a piece up to 200 nm in size, at the 2nd stage they are crushed into pieces up to 80 mm, divided into fractions +80 mm, 10-80 mm and - 10 mm, at the 3rd stage the obtained fraction of 10-80 mm is crushed on a rotary crusher in closed cycle with a single-screen vibrating screen with 10 × 10 mm sieve cells, a 10 mm fraction is obtained, which is combined with a previously obtained 10 mm fraction and subjected to grinding in two stages: on the 1st centrifugal grinding and separation to a particle size of 0.15 mm, which at the 2nd stage is subjected to air-centrifugal classification, slag grain size 0.06-0.15 mm feed on the metering and mixing unit, determine the content of vanadium pentoxide in the slag, depending on which set of chemical additives and soda fed required number of components and additives in the batch mixer are blended, fed to a granulator, and then finished granules is directed to oxidizing roasting.

According to claim 2 of the invention, the magnetic separation of the charge is carried out at all stages of crushing and grinding stage using suspended self-unloading iron separators with permanent magnets. In paragraph 3 of the formula, it is noted that the charge preparation process is carried out using an automated control system based on a programmable controller.

The problem is solved using the signs specified in the 4th claim that are common with the prototype, such as a line for preparing a vanadium-containing slag-batch mixture for oxidative firing, containing a receiving hopper, jaw crusher installed during the process and interconnected by transport communications, slag storage bins and kilns, and distinctive salient features, such as the line includes a vibrating two-screen screen installed after the jaw crusher, a torus, single-screen vibrating screen and a grinding-classifying complex made in the form of one or more technological threads, including each: receiving hopper, metal screening hopper, centrifugal mill, one output of which is connected to the receiving hopper, and the other with an air-centrifugal classifier, which is connected one exit to the dosing and mixing section through, for example, a conveyor, and the other to a group of cyclones connected by one exit to the dosing and mixing section through, for example, nyuera or to the big bags for collecting converter slag, and another outlet to the bag filter connected to the metering and mixing section by, for example, a conveyor or to the big bags to collect converter slag, while the metering and mixing section includes finely ground slag silos chemical waste and soda ash, a tape weighing batcher, over which a concentrator is installed to determine the content of vanadium pentoxide in the charge, which is included in the general scheme (an automated control system for technological process) APCS, and the weigher is associated with the dispenser by elevator-weights, connected with a mixer, a storage silo, and is further set before kiln-batch granulator.

According to claim 5, as transport communications of the technological equipment listed in claim 4, it contains belt conveyors and / or screw feeders and / or elevators.

In paragraph 6 of the claims, it is noted that the line is equipped with an automatic process control system based on a programmable controller.

The feature of placing iron separators in the technological line is reflected in paragraph 7 of the claims, namely, after a jaw crusher and a rotor crusher, suspended self-unloading permanent magnet separators are installed above the conveyor belts in front of the receiving hoppers of the grinding and classification complexes.

The above set of essential features both in the method and in the device (technological line) allows to obtain the following technical result during the implementation of the invention - obtaining a slag of a given fraction, the ability to quickly control the degree of grinding of the charge, reducing vanadium losses during the charge preparation and firing of the charge, increasing the activity of spinel grains using the shock method of mechanical activation, reducing the content of metal inclusions, reducing slag losses during firing, reducing dust slag meat for roasting furnaces, an increase in total vanadium extraction step chemical redistribution and as a consequence, increase in production of vanadium products, environmental improvement.

The technical result is achieved due to the rational layout and application of new high-tech equipment at all stages of the charge preparation, fundamentally different from the existing charge prototype existing on the basis of the prototype.

Processing vanadium slag to its fine grinding consists in obtaining the finished product - the target fraction of 0.060-0.150 mm with a minimum content of metallic iron, which is a harmful impurity in the charge.

As experimental work has shown, at the stage of preparatory crushing of converter slag, it is advisable to use crushing and grinding equipment, which uses the principle of impact destruction of a material, such as rotary crushers, which are highly efficient due to:

- high performance;

- a high degree of crushing of the material;

- selective grinding by weak grains, phase boundaries, grain size;

- grinding slag in its weak points, because fracture occurs with a large number of collisions by accumulating fracturing and loosening by high-frequency impact, and half of the grinding is due to interaction between each other.

To obtain finely ground slag, efficient separation of particles in micron ranges and to regulate the fineness of ground slag over a wide range, the authors propose using a centrifugal mill and a pneumatic centrifugal classifier operating in a closed-cyclic manner.

A centrifugal mill is characterized by a narrow (homogeneous) fractional composition of the finished product - a small presence of thin and coarse grades, and impact destruction of the material allows to obtain fine grinding products with a high specific surface and physicochemical activity of substances and to improve the physical and technical properties of the finished materials.

KC air-centrifugal classifiers are used in production lines for producing finely dispersed materials and are intended for high-precision separation of finely dispersed particles by size or density (with one-dimensional particles) in the particle size range from 10 to 160 microns with a given separation boundary with a capacity of 0.1 to 20 t / h, allow you to get several narrow fractions of the finished product in a given range of fineness (0,020-0,500 mm) with a capacity of 1 to 12 t / hour.

In the grinding complex, the centrifugal-shock method of dry grinding and the dynamic method of classifying materials are used. Centrifugal impact grinding products have characteristics and indicators that cannot be achieved using other grinding methods: a narrow predetermined particle size distribution, high physicochemical activity and specific surface area of the particles.

The iterative process of the complex (grinding and separation of the finished product) allows to reduce the specific energy consumption and to avoid the formation of overgrown classes due to the continuous removal of the finished product from the grinding process. The reduction in energy consumption for grinding materials compared to other grinding methods is 12-56%.

It should be noted that during rotary crushing, and especially during centrifugal impact grinding, mechanical activation occurs.

The particles crushed in this way have increased chemical activity, which significantly increases the intensity of the physicochemical processes that occur during firing in the furnace, which ultimately leads to an increase in vanadium recovery.

The operating features of the proposed KI grinding complexes are: the absence of grinding media, high utilization of equipment, stable particle size distribution of grinding products, reduction in the frequency and time of service.

For the efficient separation of metal inclusions, both large and smallest, on the production line, the authors proposed the installation of suspended self-unloading magnetic separators (iron separators) operating on permanent magnets.

For accurate dosing of all components of the mixture (vanadium-containing slag, soda, chemical waste and dust from gas purification) and to obtain the finished mixture, a dosing unit with an automatic control system is designed. The necessary parameters are set from an automated workstation for dosing the initial components, including changing the amount of soda entering the dispenser, and then to the mixer after receiving the task from the RKTs-1M device, by controlling it using PC and modern software,

In order to increase the degree of conversion of vanadium into a soluble form during the firing process, a granulation step of the charge is provided.

The proposed processing line of the charge preparation is presented in the drawing.

The line for preparing a vanadium-containing slag batch mixture for oxidative roasting contains a receiving hopper 1 installed during the technological process and interconnected by transport communications, a jaw crusher 2, slag storage bins 3, and kilns 4. In addition, it includes a vibratory two-cell installed after the jaw crusher 4 screen 5, rotor crusher 6, single-screen vibrating screen 7 and grinding-classifying complex 8, made in the form of two technological threads (installation in the line is possible and one or more threads, depending on the required production line capacity), including each: receiving hopper 9, metal screening hopper 10, centrifugal mill 11, one output of which is connected to a receiving hopper 9, and the other with an air-centrifugal classifier 12, which is connected one exit to the dosing and mixing section 13 through, for example, a conveyor 14, and another to a group of cyclones 15 connected by one exit to the dosing and mixing section 13 through, for example, a conveyor 14 or to big bags 16 for collecting converter slag, and another outlet to a bag filter 17 connected to the dosing and mixing section 13 via, for example, a conveyor 14 or to big bags 16 for collecting converter slag. The dosing and mixing section 13 includes fine slag silos 18, chemical waste 19 and soda ash 20, a tape weighing batcher 21, over which a concentrator 22 is installed to determine the content of vanadium pentoxide in the charge, which is included in the general scheme of industrial control system (not shown in the drawing) . The weighing batcher 22 is connected by means of an elevator 23 to a weighing batcher 24 connected to a mixer 25, a storage silo 26 and additionally installed in front of the kiln 4 with a charge granulator 27.

As transport communications of the technological equipment listed above, it contains belt conveyors and / or screw feeders and / or elevators.

The process of preparing a vanadium-containing slag soda mixture for oxidative roasting involves crushing slag, magnetic separation, grinding, mixing it with chemical additives for subsequent roasting. Before firing, the resulting mixture is granulated, and crushing is carried out in several stages with classification by size, at the first preparatory stage they are crushed into pieces up to 200 mm in size, at the second stage they are crushed into pieces up to 80 mm, divided into fractions +80 mm, 10-80 mm and - 10 mm, at the 3rd stage, the obtained fraction of 10-80 mm is subjected to crushing on a rotary crusher in a closed cycle with a vibrating single-sieve screen with 10 × 10 mm sieve cells, a fraction of 10 mm is obtained, which is combined with previously the obtained fraction is 10 mm and is subjected to grinding in two stages: on the 1st centrifugal th grinding and separation to a particle size of 0.15 mm, which is subjected to air centrifugal classification at the 2nd stage, slag with a grain size of 0.06-0.15 mm is fed to the metering and mixing unit, the content of vanadium pentoxide in the slag is determined, depending on which set the amount of chemical additives and soda, serves the required number of components of the mixture and additives in the mixer, mix, serves in the granulator, then the finished granules are sent to oxidative firing.

The magnetic separation of the charge is carried out at all stages of crushing and grinding stage using suspended self-unloading iron separators with permanent magnets.

The charge preparation process is carried out using an automated control system based on a programmable controller.

The automated process control system provides automated control, monitoring, accounting and reporting functions, which allows for the implementation of a sequence of technological operations and the maintenance of effective regulation parameters, and also eliminates the need for personnel to stay at workplaces located in the area of operating units, reduces or eliminates the effects of production factors per staff.

ACS TP charge preparation provides:

- input of input parameters of source materials and their adaptation to the control system;

- control of technological process parameters;

- control (diagnostics) of the state of mechanisms and assemblies;

- automatic control of mechanisms and systems;

- technological protection against emergencies, including blocking;

- alarm system status, including emergency;

- information services and reporting on the work of the department.

Automated process control systems are formed on the basis of sensors and primary converters of the state control system (GSP) system with unified outputs of 0 ... 5 mA, 4 ... 20 mA direct current signals, mainly non-contact. As a regulatory control and converting (for communication with a personal electronic computer (PC)) device, a microprocessor controller of regulatory and logical modification is used.

The use of microprocessor technology provides convenience, visibility, ease of control and speed of intervention in the process, and also reduces the number of expensive instrumentation (secondary devices, control devices, instrumentation panels, etc.) and significantly reduces the need for space required for placement (CTS), compared to traditional instrumentation solutions.

A specific embodiment of the invention.

Local slag (decks of 1,500 × 1,200 × 1,000 mm in size) is unloaded from the wagons to the site, where they are broken up with a copier ball into pieces up to 200 mm.

In the process of breaking up the slag, magnetize the metal (large bins) with a magnetic washer. To more thoroughly remove the sardardian, the decks are repeatedly turned over with a grab.

Next, the slag, broken into pieces up to 200 mm, is fed with a grab into the receiving hopper 1, from the hopper, the slag enters the SM-11B jaw crusher 2 with an exit slit size of 80 mm. In it, primary crushing of slag is carried out. Next, crushed slag is conveyed through a conveyor belt 3 to a vibrating double-screen screen 5 with sieves 80 × 80 and 10 × 10 mm to obtain products of classes +80 mm, 10-80 mm and 0-10 mm. Converter slag, which is distinguished by good crushability, is divided into classes of 10-80 mm and 0-10 mm. A flask-shaped skardnik that passes through jaw crusher 2 enters the oversize product. Oversize product of class +80 mm (skardovnik) is poured onto a specially designated area, a product of class 10-80 mm is passed through a 6 DR 6 × 6 rotary crusher operating in a closed cycle with single-screen vibrating screen 7 with sieve cells 10 × 10 mm, to obtain slag with a particle size of 0-10 mm; 0-10 mm fraction is sent to the slag storage hopper 3. Over the conveyor conveyor 28 crushing products of +10 mm class and over the conveyor conveyor 29 fractions 0-10 mm in front of the slag warehouse 3 suspended self-unloading iron separators 31 are installed, on which metal inclusions of classes 10- are extracted 80 mm and 0-10 mm.

The iron-free slag of fractions of 0-10 mm, partially crushed, is stored in the intermediate silos of the slag storage 3, because to ensure uninterrupted operation of the pyrohydrochemical redistribution, a constant supply of at least 300 tons should be provided.

From the hoppers, slag with a grain size of 0-10 mm is fed to centrifugal grinding in aggregates for grinding and separation of converter vanadium slag, represented by two parallel technological threads (A, B). On each thread, along with grinding in the first stage, the slag is classified in the air stream to a predetermined particle size of 0.15 mm. Unrefined slag particles of more than 0.15 mm together with metal inclusions are deposited in the hopper for large product 10. This slag is returned to centrifugal grinding after extraction of metal inclusions using a suspended self-unloading iron separator 31 with a permanent magnet.

Further, slag with a particle size of 0-0.15 mm is fed to the air-centrifugal classification (centrifugal mill 11 МЦ-1.25 and air-centrifugal classifier 12 КЦ) for separation according to a given size of the boundary grain, in this case, up to 0.06 mm. Slag with a particle size of 0.06-0.15 mm is loaded into silos 16 on each of the two lines of the metering and mixing unit. Slag with a particle size of 0-0.06 mm from the air-centrifugal classifier is fed into cyclones 15 and bag filters 17, where it is captured and removed. Slag fractions of 0-0.06 mm can be set for pelletizing or briquetting.

Vanadium-containing slag of the class 0.06-0.15 mm, received at the metering and mixing unit 13, is accumulated in silos 18. Chemical waste and soda ash are fed into separate silos 19 and 20 on each line from big bags. The slag along the belt conveyor 21 and the elevator 23 is set into the weighing machine 24. When passing the slag along the belt conveyor 21 to the weighing doser 24, the content of vanadium pentoxide in the slag is determined by the radioactive isotope concentrator 22 RKTs-1M. Next, set chemical waste and soda. At this stage, mechanization of processes using an automated control system is provided, providing the ability to set the necessary parameters for the dosage of the starting components, including changing the amount of soda. Its supply to the dispenser is carried out according to the stoichiometric coefficient of the ratio of vanadium pentoxide and soda in the mixture. Next, the charge is fed into the mixer 25 after receiving the job from the device RKC-1M. The cycle is repeated several times at the command of the dispenser-weights 24 until the necessary mass is set.

Next, the starting components are loaded into the mixer 25 using a capsule through the loading neck, where they are mixed.

After mixing, the finished mixture through the valve is discharged into the storage silo 26. The cycle is repeated.

From the storage silo 26, the finished slag-batch mixture is continuously fed into the granulator of the mixture 27 and then in the form of granules 2-3 mm in size into the kiln 4 for oxidative firing in the amount of 3 t / h.

The proposed production line and method for preparing vanadium-containing slag for oxidative firing is underway at the Chusovskoy Metallurgical Plant OJSC.

From the description and practical application of the present invention, specialists will be obvious and other private forms of its implementation. This description and examples are considered as material illustrating the invention, the essence of which and the scope of patent claims are defined in the following claims by a combination of essential features and their equivalents.

Claims (7)

1. A method of preparing a vanadium-containing slag batch mixture for oxidative firing, including slag crushing, magnetic separation, grinding, mixing it with chemical additives for subsequent firing, characterized in that the mixture is granulated before firing, and slag crushing is carried out in several stages with size classification , at the 1st preparatory stage they are crushed into pieces up to 200 mm in size, at the 2nd stage - into pieces up to 80 mm, divided into fractions +80 mm, 10-80 mm and - 10 mm, at the 3rd stage the obtained fraction 10-80 mm subjected to crushing a rotary crusher in a closed cycle with a vibrating single-sieve screen with 10 × 10 mm sieve cells, a 10 mm fraction is combined with a previously obtained 10 mm sieve and processed in two stages: centrifugal grinding and separation to particle size are carried out on the 1st 0.15 mm, which is subjected to centrifugal grinding and air-centrifugal classification at the 2nd stage, and slag with a particle size of 0.06-0.15 mm is fed to the metering and mixing unit, the content of vanadium pentoxide in the slag is determined, depending on which serve the necessary the amount of chemical additives and soda to mix with slag. 2. The method according to claim 1, characterized in that the magnetic separation of the charge is carried out at all stages of crushing and grinding steps using suspended self-unloading iron separators with permanent magnets. 3. The method according to claim 1, characterized in that the process of preparing a vanadium-containing slag-batch mixture is carried out using an automated control system (ACS) based on a programmable controller. 4. A production line for preparing a vanadium-containing slag batch mixture for oxidative roasting, containing a receiving hopper, a jaw crusher, slag storage bins and kilns installed along the process and connected by transport communications, characterized in that it includes a double-screen vibrating after jaw crusher screen, rotor crusher, single-screen vibrating screen and grinding-classifying complexes made in the form of one or more technological their threads, including each: receiving hopper, metal screening hopper, centrifugal mill, one output of which is connected to the receiving hopper, and the other with an air-centrifugal classifier, which is connected by one output to the dosing and mixing section, and the other by a group of cyclones connected by one exit to the dosing and mixing section or to big bags for collecting slag, and another exit to a bag filter connected to the dosing and mixing section or to big bags to collect converter slag, while the dosing section and mixing includes silos of finely ground slag, chemical waste and soda ash, a tape weighing batcher, over which a concentrator is installed to determine the content of vanadium pentoxide in the charge, while the weighing batcher is connected via an elevator to a weighing batcher connected to a mixer, a storage silo, and additionally a charge granulator installed in front of the kiln. 5. The line according to claim 4, characterized in that as transport communications it contains belt conveyors and / or screw feeders, and / or elevators. 6. The line according to claim 4, characterized in that it is equipped with an ACS based on a programmable controller. 7. The line according to claim 4, characterized in that after the jaw crusher and rotor crusher, suspended self-unloading magnetic iron separators are installed above the conveyor belts in front of the receiving hoppers of the grinding and classification complexes.

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