CN115747484A - Calcification reduction dealkalization method for vanadium extraction tailings - Google Patents

Calcification reduction dealkalization method for vanadium extraction tailings Download PDF

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CN115747484A
CN115747484A CN202211567915.1A CN202211567915A CN115747484A CN 115747484 A CN115747484 A CN 115747484A CN 202211567915 A CN202211567915 A CN 202211567915A CN 115747484 A CN115747484 A CN 115747484A
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gas
rotary kiln
reduction
consolidation
microwave
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郑富强
胡兵
刘臣
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Zhongye Changtian International Engineering Co Ltd
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Zhongye Changtian International Engineering Co Ltd
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Abstract

The invention provides a calcification reduction dealkalization method of vanadium extraction tailings, which prepares silicon-free high-temperature released CO by pelletizing pretreatment of a composite low-temperature curing agent and the vanadium extraction tailings 2 The pellet raw material of (1); the strength of the pellets is enhanced by adopting a hot air drying-microwave consolidation process; then adopting a rotary kiln to carry out reduction roasting, leading alkali metal in the vanadium extraction tailings to enter a gas phase to be removed through dust removal treatment, obtaining slag phase with high iron and vanadium metallization rate, being capable of being directly used in a blast furnace and effectively removing the iron and the vanadiumThe alkali metal in the vanadium extraction tailings is removed, the vanadium extraction tailings are recycled in the iron making process, the recovery rate of valuable elements in the vanadium extraction tailings is improved, and the capacity of treating the vanadium extraction tailings in a blast furnace is improved.

Description

Calcification reduction dealkalization method for vanadium extraction tailings
Technical Field
The invention relates to a treatment method of vanadium extraction tailings, in particular to a method for treating vanadium extraction tailings by adopting a reduction method, and belongs to the technical field of solid waste treatment and metallurgy.
Background
Most of iron elements rich in the vanadium extraction tailings are oxidized into hematite, and currently, the iron elements are utilized by a magnetization roasting method, a spiral flow channel method, a magnetic separation method, a flotation method and the like. Various studies on the recovery of iron from tailings have focused mainly on both the pyrogenic process and the wet process. Some steel mills sinter or pelletize the tailings and then return them to the blast furnace, but the blast furnace cannot utilize all of the tailings. The first reason is that the iron content in the extracted vanadium tailings is low, so that the comprehensive iron grade entering the furnace is reduced, and the coke ratio is improved. And secondly, the content of alkali metal in the vanadium extraction tailings exceeds the bearing limit of the blast furnace, so that the air permeability of a blast furnace material column is deteriorated, and the smooth operation of the blast furnace is influenced. And thirdly, the tailings contain toxic hexavalent chromium and pentavalent vanadium, so that potential secondary pollution risk exists in the recovery process. Therefore, non-blast furnace iron making technology is favored by a plurality of scholars, and the reduction milling method is most researched. Reducing ferric iron in tailings into metallic iron particles by reduction roasting, and then recovering iron by ore grinding and magnetic separation. The iron in the tailings recovered by the wet process is leached by adopting sulfuric acid under pressure. The iron in the tailings is dissolved during the pressure acid leaching and crystallised out of solution as copperas. Then, glucose is used as a substrate, and a hydrothermal method is adopted to synthesize the spherical nano iron oxide. However, the methods only recover part of valuable elements in the vanadium extraction tailings, still generate a large amount of waste, and do not solve the problem that the vanadium-containing tailings are difficult to recycle due to high alkali metal content.
The method for extracting vanadium from tailings mainly comprises a sodium roasting-water leaching method and a direct acid leaching method. The basic principle of the sodium salt roasting-water leaching process is to add sodium salt for roasting to convert low-valence vanadium into water-soluble pentavalent vanadium. Analysis of the vanadium extraction tailings after sodium roasting showed that some vanadium-containing spinels were not oxidized due to the presence of silicates therein. Some of the smaller vanadium particles enter the vitreous and become insoluble vanadium-containing compounds. Therefore, more vanadium still exists after the tailings are subjected to secondary vanadium extraction. The other method is a direct acid leaching method, and atmospheric pressure leaching or pressure leaching can be adopted. The leaching agent is generally sulfuric acid, and a small amount of oxidant and catalyst are added. When high-concentration sulfuric acid is used, equipment corrosion is increased. Hydrogen fluoride is often used as a catalyst in the process, which can exacerbate environmental risks. The pressure leaching is an acid leaching reaction which takes sulfuric acid as a leaching agent and hydrogen peroxide as an oxidizing agent. Compared with the normal pressure acid leaching, the method has the defects of high equipment requirement, small treatment capacity and the like.
In order to solve the dealkalization research of vanadium extraction tailings, researchers propose that calcium oxide or magnesium oxide is added for pressure heating leaching to destroy a sodium-containing phase, so that sodium is leached into a solution and then removed. The main phases in the vanadium extraction tailings are pyroxene solid solution, iron oxide and olivine. The sodium removal rate is not high whether the normal pressure inlet and outlet method or the pressure leaching method is adopted, the pressure leaching is required in the process, the equipment investment is high, the operation is discontinuous, and the investment cost and the treatment cost of enterprises are increased. The existing utilization research aiming at vanadium extraction tailings mostly focuses on extracting and utilizing part of valuable elements, a large amount of wastes are still generated in the extraction process, the environment is damaged, and the problem of recycling comprehensive utilization of the vanadium extraction tailings is not solved essentially.
The traditional reduction roasting volatilization method needs high temperature and long time for removing alkali metal, and the high reduction temperature can cause serious caking rings in the reduction process. If the powder is not agglomerated before reduction, the agglomeration and ring formation are serious due to large powder amount, if the powder is agglomerated, the addition amount is large due to the adoption of binders such as traditional bentonite and the like, the silicon content in the bentonite is high, the silicon can react with vanadium extraction tailings at high temperature, and the difficulty of removing alkali metal can be increased by the formed compound. For complex and stable solid solutions containing various elements such as sodium, potassium, silicon, titanium, iron, magnesium, aluminum, manganese and the like, alkali metals in the complex and stable solid solutions cannot be removed by the traditional reduction volatilization method.
Disclosure of Invention
Aiming at the problems that the vanadium extraction tailings generated in the vanadium industry in the prior art contain a large amount of iron and vanadium and also contain high alkali metal elements; in the process of returning to the sintering-blast furnace process, the low melting point and the adhesion of grate bars of the sintering ore can be caused by the over-high content of alkali metal, and the process phenomena of tuyere sleeve damage, furnace lining corrosion and the like can be caused in the reduction process of the blast furnace. In the prior art, the reduction roasting volatilization method for removing alkali metal is high in temperature, long in time and high in reduction temperature, and incomplete alkali metal removal can cause serious caking and ring formation in the reduction process and influence the operation of a blast furnace and the grade of iron; in the prior art, the vanadium extraction tailings are treated by adopting a pelletizing or agglomeration pretreatment process, and the technical problems that new impurity silicon is introduced, the strength of the pellets is not enough and the pellets are easy to crack exist. In order to solve the problems, the invention provides a calcification reduction dealkalization method of vanadium extraction tailings, which prepares a pellet raw material which does not contain silicon and releases CO2 at high temperature by pelletizing pretreatment of a composite low-temperature curing agent and the vanadium extraction tailings; the strength of the pellets is enhanced by adopting a hot air drying-microwave consolidation process; and then, reducing roasting is carried out by adopting a rotary kiln, so that alkali metal in the vanadium extraction tailings enters a gas phase and is removed through dust removal treatment, the obtained slag phase has high iron and vanadium metallization rate, the alkali metal can be directly used for a blast furnace, the alkali metal in the vanadium extraction tailings is effectively removed, the vanadium extraction tailings are recycled in an iron making process, the recovery rate of valuable elements in the vanadium extraction tailings is improved, and the capacity of treating the vanadium extraction tailings in the blast furnace is improved.
According to the technical scheme provided by the invention, the method for calcifying, reducing and dealkalizing the vanadium extraction tailings is provided.
A calcification reduction dealkalization method of vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and the composite low-temperature curing agent, and pelletizing to obtain green pellets;
2) Carrying out hot air drying and microwave consolidation on the green pellets in sequence to obtain consolidated pellets;
3) Conveying the consolidated pellets to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material.
Preferably, the tail gas subjected to desulfurization treatment in the step 3) contains CO 2 Exhaust gas will contain CO 2 The waste gas is divided into two parts, one part contains CO 2 Waste gas transportationFeeding to a rotary kiln; a part containing CO 2 The exhaust gas is sent to the microwave consolidation step, and the gas discharged from the microwave consolidation step is sent to the hot air drying step.
Preferably, the CO-containing feed to the rotary kiln 2 Waste gas is input from the middle kiln body of the rotary kiln.
Preferably, the cooling in step 3) is performed by a semi-dry method, specifically:
301 Passing the water through an atomization system to obtain atomized water;
302 Conveying the reducing material into a semi-dry cooling device, and introducing atomized water into the semi-dry cooling device; cooling the reduced material with atomized water, absorbing heat in the reduced material with atomized water, and water-gas reaction of atomized water and residual carbon in the reduced material to obtain CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
Preferably, a part of the CO-containing component 2 Conveying the waste gas to a rotary kiln; a part containing CO 2 Conveying the waste gas to a microwave consolidation step, and conveying the gas discharged from the microwave consolidation step to a hot air drying step; the remaining CO-containing 2 The waste gas is conveyed to an atomization device, and CO is dissolved in the atomized water 2 (ii) a Dissolved with CO 2 The atomized water is reformed by a semidry cooling device, and CO is obtained 2 Carrying out a Boolean reaction with the carbon residue in the reduced material, and carrying out a water gas reaction with the atomized water and the carbon residue in the reduced material to obtain a product containing CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
In the invention, the screening in the step 3) is magnetic separation, and the iron-vanadium raw material and the residual carbon are obtained through magnetic separation.
Preferably, the waste heat utilization is specifically waste heat power generation.
Preferably, the residual carbon is screened to obtain fine-particle-size coke powder and coarse-particle-size coke powder, the fine-particle-size coke powder is used as a sintering ingredient, and the coarse-particle-size coke powder is conveyed to the rotary kiln. The iron vanadium raw material is conveyed to a blast furnace. The alkali-containing dust is obtained through the first dust removal treatment and the second dust removal treatment.
In the invention, the composite low-temperature curing agent in the step 1) is obtained by uniformly mixing one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride and calcium sulfate with one or more of starch, coal tar and molasses.
In the invention, the mixing weight ratio of the vanadium extraction tailings and the composite low-temperature curing agent is 1.
In the present invention, the green pellets have a moisture content of 5 to 20% by weight, preferably 8 to 12% by weight.
In the present invention, the green pellets have a particle diameter of 2 to 12mm, preferably 3 to 8mm.
Preferably, in the step 2), the microwave consolidation step is performed by introducing CO-containing gas 2 And steam, containing CO 2 And the gas of the water vapor is conveyed to the microwave consolidation step, and the gas discharged from the microwave consolidation step is conveyed to the hot air drying step.
Preferably, it contains CO 2 The gas with steam is added with steam and CO 2 Any one of hot air of blast furnace gas, coke oven gas or hot tail gas after converter gas combustion, direct reduction hot tail gas and lime kiln hot tail gas.
In the present invention, CO is contained 2 CO in gas with water vapor 2 The concentration is 10 to 50%, preferably 20 to 40%.
In the present invention, CO is contained 2 The humidity of the gas with water vapor is 10g/m 3 ～100g/m 3 Preferably 20g/m 3 ～50g/m 3 。
In the invention, in the step 3), the consolidated pellets and the coke powder are mixed and then are conveyed to a rotary kiln for reduction roasting. The weight ratio of the consolidated pellets to the coke powder is 1.1-1.5, preferably 1.
Preferably, coal is injected from the kiln head of the rotary kiln in the reduction roasting process. The weight ratio of the injected coal to the consolidated pellets is 0.1-1:1, preferably 0.2-0.5.
Preferably, the hot air drying process is two-stage hot air drying, and comprises a hot air drying stage I and a hot air drying stage II.
Preferably, the microwave consolidation process is two-stage microwave consolidation and comprises a microwave consolidation stage I and a microwave consolidation stage II.
The green pellets sequentially pass through a hot air drying section I, a hot air drying section II, a microwave consolidation section I and a microwave consolidation section II to obtain consolidated pellets.
Preferably, the drying temperature of the hot air drying I stage is 60-100 ℃, and the drying time is 2-20 min. The drying temperature of the hot air drying section II is 100-250 ℃, and the drying time is 2-20 min. After the hot air drying process, the mass content of the water in the pellets is 2-8%, preferably 4-6%.
Preferably, the temperature of the microwave consolidation I section is 250-350 ℃, and the pellet retention time is 2-20 min. The temperature of the microwave consolidation II section is 350-500 ℃, and the pellet retention time is 2-20 min. The microwave power density in the microwave consolidation procedure is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
Preferably, the rotary kiln is a direct reduction rotary kiln.
A direct reduction rotary kiln comprises a kiln head, a kiln body and a kiln tail. The kiln head is provided with a burner. The direct reduction rotary kiln is of a cylindrical structure, and the side wall of the kiln body of the direct reduction rotary kiln is formed by stacking refractory bricks. A gas conveying pipeline is arranged in the refractory brick on the side wall of the kiln body. The inner side wall of the kiln body is provided with a nozzle. The nozzle is communicated with the gas delivery pipeline and the inner chamber of the direct reduction rotary kiln.
In the invention, the nozzle is arranged at the middle kiln body position of the direct reduction rotary kiln.
Preferably, a plurality of gas conveying pipelines are arranged in the kiln body and are parallel to the axial direction of the direct reduction rotary kiln.
Preferably, 2-100 gas conveying pipelines are arranged in the kiln body, and preferably 4-50 gas conveying pipelines are arranged in the kiln body.
And a plurality of gas conveying pipelines are uniformly arranged in the side wall of the direct reduction rotary kiln.
Preferably, a plurality of nozzles are provided on each gas delivery conduit.
Preferably, 2-20 nozzles are provided per gas delivery line, preferably 3-10 nozzles per gas delivery line.
Preferably, the gas delivery conduit is a helical conduit. The spiral gas conveying pipeline is vertical to the axial direction of the direct reduction rotary kiln 1 and is wound in a refractory brick of the kiln body.
Preferably, the helical gas transport pipe is provided with a plurality of nozzles.
Preferably, the helical gas transmission pipeline is provided with 2-100 nozzles, and the preferred helical gas transmission pipeline is provided with 3-50 nozzles.
In the invention, the air inlet end of the gas conveying pipeline is connected with the blower.
Preferably, the gas delivery conduit is terminated with a gas bleed valve, and the gas bleed valve is located downstream of the nozzle.
Preferably, the gas transmission pipeline is a reducing pipeline. The inner diameter of the gas delivery pipe gradually decreases from the gas inlet end to the location where the nozzle is disposed.
Preferably, the inner diameter of the gas delivery pipe is gradually increased from the position where the nozzle is provided to the position of the gas release valve.
Preferably, the ratio of the inner diameter of the gas delivery conduit at the nozzle location to the inner diameter of the gas delivery conduit at the gas inlet end is 1.5 to 4, preferably 1:2-3.
Preferably, a pressurizing backflow-preventing fin is arranged on the inner wall of the gas conveying pipeline.
Preferably, the cross section of the pressurizing backflow-preventing fin is of a splayed structure. The tail end of the pressurizing backflow-preventing fin with the splayed structure is connected with the inner wall of the gas conveying pipeline and is positioned at the upstream.
Preferably, the angle between the pressurized backflow-preventing fins and the inner wall of the gas conveying pipeline is 20-80 degrees, and preferably 30-60 degrees.
Preferably, a temperature measuring element is arranged on the inner wall of the gas conveying pipeline.
Preferably, the inner walls of the gas conveying pipelines positioned at each section of the kiln head, the kiln body and the kiln tail of the direct reduction rotary kiln are respectively and independently provided with a temperature measuring element.
In the invention, the vanadium extraction tailings are pelletized, dried and consolidated to obtain consolidated pellets, and the consolidated pellets are subjected to reduction roasting by a rotary kiln. In the rotary kiln, alkali metal has a low boiling point, enters a gas phase and is discharged out of the rotary kiln along with flue gas; the flue gas discharged from the rotary kiln is subjected to dust removal treatment (settling chamber) to obtain settling ash containing alkali metal. Reducing the oxides of iron and vanadium in a rotary kiln to obtain simple substance iron and vanadium, or reducing the simple substance iron and vanadium into low-price iron (+ 2-price) and low-price vanadium (+ 3), entering a slag phase, and discharging from a kiln head of the rotary kiln; then cooling to obtain the reduced material containing iron and vanadium. The reduced material containing iron and vanadium can be directly used as the raw material of the blast furnace.
Compared with the common reduction and volatilization method, the composite pellet (green pellet) adopted by the invention has the characteristics of faster and more uniform carbonation reaction, higher pellet strength and higher production efficiency. The composite low-temperature curing agent is obtained by uniformly mixing one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride and calcium sulfate with one or more of starch, coal tar and molasses, does not contain silicon, releases CO2 at medium-high temperature, is used for calcification of a calcium binder, forms calcium carbonate with higher strength, and improves the hardness and the consolidation degree of pellets. The method for removing sodium by calcification reduction and volatilization provided by the invention has the characteristics of higher sodium removal rate and more stable production, and the semi-dry cooling has the characteristics of higher waste heat utilization rate and higher cooling speed.
The reason is that:
(1) The composite low-temperature curing agent added in the pelletizing process contains the carbon-based composite binder, and the carbon-based composite binder among the raw material particles is converted into CO in the drying and solidifying process 2 Direct supply of CO for carbonation 2 Gas, change the prior unreflectedShould nuclear model, avoid traditional CO 2 The outside and the inside of the pellet are carbonated synchronously under the condition that the pellets need to diffuse from the outside to the inside, and the influence that the gas diffusion is hindered by an outer compact calcium carbonate film is avoided. Preferably, the CO is also reduced by using the form of 3-8mm pellets (green pellets) 2 Diffusion resistance inside the pellets.
(2) The composite low-temperature curing agent contains calcium oxide/calcium hydroxide and a carbon-based composite binder. In the green pellet stage, the colloidal calcium hydroxide and the carbon-based composite binder can ensure the strength of the pellets; in the process of dry consolidation, although the bonding strength of the dry calcium hydroxide is low under the condition of higher temperature, the carbon-based composite binder can still provide certain strength for the pellets after dehydration, and a large amount of newly generated CO is in the pellets 2 The carbonation reaction speed can be accelerated, the amount of the newly generated calcium carbonate microcrystals is more than that of the conventional method, the combination of the two methods can ensure the strength of the pellets in the drying process at higher temperature, the production efficiency can be improved by two measures of increasing the reaction temperature and increasing the material bed height, and the strength and the production efficiency are considered.
(3) The carbonation consolidation process adopts a mode of hot air drying and microwave heating drying consolidation, the microwave heating consolidation has the characteristic of heating the pellets from inside to outside, and the temperature and CO inside and outside the pellets are met 2 The atmosphere condition and the carbonation reaction rate are consistent, and a double-layer structure with hard outside and loose inside can not be generated. In addition, the carbon-based composite adhesive has extremely strong wave-absorbing property, microwave hot spots can occur under microwave radiation, the temperature can be obviously higher than the ambient temperature, a high-temperature phenomenon can occur in a local micro-area with the carbon-based composite adhesive, and the carbon-based composite adhesive is converted into CO in the micro-area 2 Reacts with water vapor and calcium hydroxide in a contact way, has higher temperature and forms high-temperature and high-CO in a micro area 2 The reaction environment of high water vapor and high calcium is characterized in that the carbonation reaction is rapidly carried out to generate calcium carbonate microcrystals, the formed calcium carbonate microcrystals can drive mass point migration by microwaves under the non-thermal effect of the microwaves, the microcrystals rapidly grow up, adjacent particles are tightly connected together, and high-strength guarantee is provided for the pellets.
(4) The multi-orifice rotary kiln (the rotary kiln with air intake from the kiln body) is adopted for reduction roasting, the temperature field in the kiln can be effectively adjusted through the multi-orifice of the kiln body, the temperature of the high-temperature area is reduced by supplying air to the high-temperature area, the material temperature is prevented from being melted and formed due to overhigh temperature, the combustion efficiency of the reduction gas in the kiln is improved by supplying air to the kiln tail section in the kiln, the gas temperature in the kiln tail direction is increased, the high-temperature area is effectively prolonged, and a longer-time high-temperature roasting environment is provided for material reduction.
(5) The semi-dry cooling method adopted by the invention can convey atomized water to a hot reduction product to carry out countercurrent direct heat exchange cooling, and the reduction product contains high-temperature residual coal (residual carbon or residual coke) which is partially unburned and reacts with water vapor and CO 2 Endothermic reactions occur during the contact:
C+CO 2 ＝2CO
C+H 2 O＝H 2 +CO
the temperature of the reduction product is further reduced through the endothermic reaction of the coal gas reforming reaction and the Boolean reaction, so that the reduction product is rapidly cooled, and the reduction material containing iron and vanadium with high metallization rate is obtained.
Aiming at the problem that in the prior art, the pellets are in a drying and consolidating process, CO 2 Gas can only diffuse into the pellets from the outside of the pellets, so that the binder (such as calcium hydroxide) on the outer layer of the outer pellets is preferentially mixed with CO 2 React to form a compact calcium carbonate layer, which hinders CO 2 The gas continuously diffuses into the pellet, so that calcium carbonate cannot be formed inside the pellet, and the overall strength of the pellet is influenced. In the invention, a composite low-temperature curing agent (one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride and calcium sulfate and one or more of starch, coal tar and molasses) is added in the pelletizing process, and in the pellet drying and consolidating procedure, carbon-based composite binders (starch, coal tar and molasses) in the pellet core (inside) can release CO under the low-temperature condition of drying and consolidating 2 And H 2 O, release CO 2 And H 2 The O reacts with the binder (such as calcium hydroxide) in the pellets to form a calcium carbonate consolidation structure uniformly in the whole pellets; so that all the positions in the whole pellet are formedThe calcium carbonate with higher strength is consolidated, and the strength of the whole pellet is improved. In the technical scheme of the invention, the carbon-based composite binder among the raw material particles is converted into CO in the drying and solidifying process 2 And H 2 O, directly providing CO required for the internal carbonation reaction of the pellets 2 Gas and H 2 O steam environment, changes the prior unreacted nuclear model, and avoids the traditional CO 2 The condition that the carbon dioxide needs to diffuse from the outside of the pellet to enter the inside of the pellet, the outside and the inside of the pellet are carbonated synchronously, the influence that the dense calcium carbonate film on the outer layer hinders the gas diffusion is avoided, and the CO is reduced 2 Diffusion resistance inside the pellets. Furthermore, from reaction kinetic analysis, compared to CO 2 Gas diffuses from the outside of the pellet to the inside of the pellet, and CO is released from the inside of the pellet by adopting the technical scheme of the invention 2 And H 2 O, CO inside the pellets 2 And H 2 The outward diffusion of O is much easier, so that the binder (such as calcium hydroxide) in the pellets reacts with CO in the presence of water vapor 2 The reaction is easier, and the obtained calcium carbonate consolidation material is more uniform.
In the invention, the carbon-based composite binder (starch, coal tar and molasses) is in a solid state or a liquid state at normal temperature, and in the drying and solidifying process and the temperature rising process, the carbon-based composite binder (starch, coal tar and molasses) is heated and decomposed to release carbon dioxide and/or water. The released carbon dioxide reacts with the binder in the pellets under the action of water vapor to form a compound for consolidation. For example, the starch employed in the present application begins to decompose at 180-200 ℃ releasing CO 2 And H 2 O; the coal tar begins to decompose at about 80 ℃ to release volatile matters; waste molasses begins to decompose at 280 ℃ to release CO 2 And H 2 And O. The carbon-based composite binder (starch, coal tar and molasses) is solid or liquid at normal temperature, and is convenient to mix with vanadium extraction tailings for pelletizing; mixing carbon-based composite binder (starch, coal tar, molasses), vanadium extraction tailings and other additives for pelletizing to form pellets, gradually decomposing under the condition of temperature rise in the drying and consolidation process to release CO 2 And H 2 O, realizes the self-release of the pellets in the process of dry consolidationCO 2 And H 2 The technical effect of O and the introduction of CO into the outside 2 And H 2 The mode of O is different, and the pellet releases CO from the interior of the pellet 2 And H 2 And O, simultaneously performing the consolidation process inside and outside the pellets, so that the pellets after drying and consolidation have a uniform-strength structure from inside to outside, and the technical problem of 'hard outside and loose inside' is solved. Meanwhile, the decomposition temperature of the carbon-based composite binder (starch, coal tar, molasses) used in the present invention cannot be too high because the drying temperature of the pellets is generally controlled below 500 ℃ (preferably below 400 ℃), and if the binder with too high decomposition temperature (above 500 ℃) is used, CO cannot be decomposed and released in the drying and consolidation process 2 And H 2 O, thereby failing to achieve CO release from the interior of the pellets 2 And H 2 Technical purpose and effect of O. Through continuous experiments of the inventor, in the process of preparing the pellets, starch, coal tar, molasses or a composition thereof is added, and the substances can release CO within the temperature range of the pellet drying and consolidating process 2 And H 2 O, the decomposition temperature of the substances is matched with the temperature of the drying and solidifying process, and CO begins to be released under the temperature condition of the drying and solidifying process 2 And H 2 O, CO required for the consolidation of the pellet interior 2 And H 2 O。
Aiming at the problems that in the prior art, the pellets are generally dried and consolidated only by adopting a hot air drying and consolidating mode, and the hot air drying mode is adopted, so that the external surface temperature of the pellets is higher, the internal temperature of the pellets is lower, and the temperature difference is larger; in order to dry the inside of the pellet, the temperature of the outside of the pellet needs to be further increased, thereby causing CO on the appearance of the pellet 2 The calcium carbonate reacts with the adhesive quickly to form a compact calcium carbonate layer, and further the formation of a consolidation structure inside the pellet is hindered. In the preferred scheme of the invention, a drying and consolidating technical means of hot air drying and microwave consolidation is adopted, compared with hot air drying which is only physical heat, the pellets are dried and consolidated in a heat transfer mode; the microwave is an energy field, and can directly act on the inside of the pellet to excite the decomposition of the carbon-based composite binder in the pellet. Thereby, the deviceThe microwave heating drying and consolidation mode can ensure that the temperature of the outside and the inside of the pellet is uniform, so that the outside and the inside of the pellet are simultaneously dried and consolidated. Through the technical means of microwave heating and the addition of the carbon-based composite binder in the pellets, the microwave directly acts on the carbon-based composite binder, and the carbon-based composite binder is synchronously decomposed to release CO while drying 2 And H 2 O, therefore, drying and consolidation are performed simultaneously. The microwave not only plays a role in heating, but also ensures the uniformity of the internal and external temperatures of the pellets, and further ensures that the carbon-based composite binders at different positions of the pellets are simultaneously decomposed, so that the positions of the pellets are simultaneously consolidated, and the composite pellets with uniform strength are formed.
The carbonation consolidation process adopts a mode of consolidation under the action of microwave, and the carbon-based composite binder in the pellets is uniformly decomposed and converted into CO under the action of microwave 2 And H 2 O, the problem that the reaction of the outer layer and the inner material of the pellet is asynchronous due to the traditional outside-in heat conduction mode is avoided, so that the temperature and the CO inside and outside the pellet are both satisfied 2 The atmosphere condition and the carbonation reaction rate are consistent, and a double-layer structure with hard outside and loose inside can not be generated. In addition, under the action of microwave, high-temperature and high-CO is formed in micro-area in the pellet 2 The reaction environment of high water vapor and high calcium, the carbonation reaction is carried out rapidly to generate calcium carbonate microcrystals, the microwave can drive the mass point to move, the microcrystals grow up rapidly, and adjacent particles are closely connected together, so that high-strength guarantee is provided for the pellets.
Therefore, the composite pellet is of a homogeneous structure through the technical means of microwave consolidation and the carbon-based composite binder, the technical problem of mass imbalance caused by pellet layering is avoided, the high-strength structure of the inside and the outside of the pellet is guaranteed, and the synergistic effect is achieved.
The inventor further finds out through experiments that the drying and consolidation mode adopting hot air and microwave has a particularly remarkable effect compared with the drying and consolidation mode adopting hot air alone or microwave alone. If the hot air drying and consolidating mode is adopted independently, the pellets are dried and consolidated in a physical heat transfer mode, and the pellets exist inside and outside the pelletsUneven temperature, and lower consolidation strength inside the pellet. If the microwave drying and consolidating mode is independently adopted, the self-moisture in the pellet is quickly lost, and the moisture in the gaps among the material molecules in the pellet is suddenly lost, so that the consolidating effect among the material molecules in the pellet is also influenced. Experiments show that the pellets are dried by adopting a hot air drying mode, so that moisture in gaps among the material molecules in the pellets is evaporated at a slow speed, the molecules in the material are gathered slowly, and the inter-molecular distance in the material is reduced; then CO released by the carbon-based composite adhesive is released through the action of microwaves 2 、H 2 The O reacts with the binder to form a consolidation structure among the molecules of the material, and the strength of the obtained composite pellet is greatly improved by a drying consolidation mode combining hot air drying and microwave consolidation.
Further, experiments show that the pellet is dried in a hot air drying and microwave consolidation mode until the moisture in the pellet is 2% -8% (preferably 4% -6%) and then the composite pellet obtained through drying and consolidation by an electromagnetic field has the strength of more than 300N/P.
In the invention, the flue gas discharged from the rotary kiln in the step 3) is subjected to dust removal treatment (to obtain settled ash containing alkali metal), reburning reaction (to further burn and release heat of unreacted reducing gas CO and the like in the flue gas), waste heat utilization (sensible heat resource utilization), and then desulfurization treatment, and the gas obtained after desulfurization is CO-containing gas 2 And (4) exhaust gas. Will contain CO 2 Part of the waste gas is conveyed to microwave consolidation and hot air drying to provide CO in the peripheral environment of the green pellets in the drying and consolidation processes 2 Atmosphere, CO 2 The calcium carbonate reacts with the calcareous binder in the green pellets to generate calcium carbonate with higher strength, so that the strength of the green pellets is improved, the pellets are prevented from bursting in the rotary kiln, and the generation amount of dust is reduced. The hot air drying and the microwave drying process just need to contain CO 2 Gas, the rotary kiln process of the process just generates CO 2 Gas, realize the inside resource utilization of technology. Containing CO 2 A portion of the flue gas is conveyed to the rotary kiln (preferably to a tunnel)Input through the middle kiln body of the rotary kiln), kneading in the rotary kiln to obtain a mixture containing CO 2 The waste gas and carbon (coal or coke powder) in the pellets are subjected to a Boolean reaction to generate CO with reducibility, and the CO directly reduces metal oxides in the pellets, so that the reduction rate and the reduction efficiency of the pellets in the rotary kiln are improved, and the metallization rate of iron and vanadium in the reducing material is improved. And, containing CO 2 And the waste gas is conveyed into the rotary kiln, so that the oxidizing atmosphere in the rotary kiln is reduced, the probability that the iron and the vanadium which are reduced into simple substances or low-price iron and vanadium are oxidized again is reduced, and the metallization rate of the iron and the vanadium in the reduced material is improved. The flue gas discharged by the rotary kiln contains CO 2 The characteristic of the process is that the drying and consolidation process needs CO 2 Further combined with the feature of containing CO 2 The gas is conveyed to the rotary kiln to play a role of generating CO 2 The gas is conveyed to a required process, so that the waste gas is recycled, and the resource utilization value of the process is improved.
The inventor finds that the reducing material discharged by the rotary kiln has the characteristics of high temperature and high carbon residue, and compared with the prior art that the reducing material is directly cooled by gas, the inventor finds that the cooling effect is special by cooling the reducing material by a semi-dry cooling process of atomized water through experiments; and reducing gases (CO and H) in the gas after the atomized water is cooled by the semidry method 2 ) The content is high, and the gas has high preheating utilization value. The invention adopts atomized water as a cooling medium to carry out a semi-dry cooling process on the reduced material, the atomized water cools the reduced material, the atomized water absorbs heat in the reduced material, and the reduced material obtains better cooling effect; and the atomized water and the residual carbon in the reduction material generate water gas reaction to obtain the product containing CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
Preferably, the gas obtained after desulfurization is CO-containing 2 The waste gas is excessive according to the gas amount required by the drying and consolidation process and the rotary kiln reduction burning processContaining CO of 2 The exhaust gas is conveyed to an atomization device, CO 2 Dissolving in water to form dissolved CO 2 The atomized water of (1). Dissolved with CO 2 The atomized water is conveyed to a semi-dry cooling device, and the semi-dry cooling device cools the reducing material; at the same time, the reduced material is dissolved with CO 2 Reforming the atomized water of (1) CO 2 Performing a Boolean reaction with the carbon residue in the reduced material, and performing a water gas reaction with the atomized water to obtain a product containing CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
The invention provides a calcification reduction dealkalization method of vanadium extraction tailings, which specifically comprises the following steps:
(1) One or more calcium salts such as calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride, calcium sulfate and the like are uniformly mixed with carbon-based composite binder such as starch, coal tar, molasses and the like to be used as the composite low-temperature curing agent. Wherein, the granularity of the calcium salt is-200 meshes and is more than or equal to 50 percent, and more preferably-325 meshes and is more than or equal to 80 percent; the proportion of the calcium salt and the carbon-based composite binder can be adjusted according to the types of the calcium salt and the carbon-based composite binder, and the mixing equipment can be a cylindrical mixer, an intensive mixer and the like.
(2) Uniformly mixing the vanadium extraction tailings and the composite low-temperature curing agent, and then pelletizing, wherein the mixing ratio of the vanadium extraction tailings to the composite low-temperature curing agent is 1:0-1:1; the blending equipment can be a cylinder mixer, an intensive mixer and the like; the water content of the mixed raw materials is 5 to 20 percent; the pelletizing equipment can be a disc pelletizing machine or a powerful disturbance pelletizing machine, the pellet granularity is preferably 3-8mm, atomized water is adopted in a water adding mode in the disc pelletizing process, the atomized water is added in a material distribution area and a 2-4 mm particle size area in a pellet disc respectively, and the adding amount of the atomized water is determined according to the moisture of raw materials and the pelletizing state.
(3) The manufactured green ball is subjected to hot air pre-drying consolidation and microwave drying consolidation, and CO is introduced in the drying and consolidation process 2 And steam, wherein the drying and consolidation can be carried out by adopting a drying grate, a steel mesh belt machine and the like combined with microwaves, the material height is 10-200 mm, and more preferably 100mm-150 mm; the gas may be added with steam and CO 2 Hot air after combustion, blast furnace gas/coke oven gas/converter gas, direct reduction hot tail gas, lime kiln hot tail gas, etc.; CO2 2 The concentration is 0 to 50 percent; humidity of 10g/m 3 ～100g/m 3 More preferably, 20g/m 3 ～50g/m 3 (ii) a The gas flow rate is 0.1-5 m/s.
(4) The consolidated pellets and coke powder are mixed and then enter a multi-orifice rotary kiln for reduction roasting, and CO is introduced into the lower part of a material layer with the highest temperature through a plurality of orifices in the reduction roasting process 2 Exhaust gases, CO in exhaust gases 2 Performing a Boolean reaction (C + CO) with the coal in the bed 2 = CO) generating reducing atmosphere in the CO reinforcing material layer, and effectively reducing the temperature of the material layer by introducing the left and right heat exchange of waste gas and the reaction heat absorption effect to prevent ring formation; air is introduced into the upper part of the material layer through the multiple spray holes, and a large amount of reducing gas and the air at the upper part of the material layer are subjected to combustion reaction to supplement heat in the kiln and improve the utilization efficiency of the reducing gas. And a certain amount of coal is sprayed from the kiln head in the reduction process to ensure the reduction atmosphere of the material bed. Wherein the proportion of the consolidated pellets to the coke powder is 1:0-1, the particle size of the coke powder is 0-15 mm, the proportion of the amount of coal sprayed into the kiln head to the consolidated pellets is 0-1:1, the particle size of the coal is 0-15 mm, the highest point temperature in the reduction process is 1100-1300 ℃, and the retention time of the material with the temperature exceeding 1100 ℃ is 1-3 h.
(5) In the reduction roasting process, kiln tail waste gas is dedusted by a settling chamber to obtain settled ash 1, then the settled ash is combusted by a reburning chamber, waste heat power generation is carried out, settled ash 2 is collected, dedusted ash is collected by a dedusting system, the dedusted waste gas is desulfurized to form waste gas containing CO2, part of the waste gas returns to the rotary kiln with the spraying holes at most, the waste gas is introduced from the lower part of a material layer at the highest temperature section, part of the waste gas is heated for carbonation solidification, and the rest of the waste gas is discharged through a chimney.
(6) The pellets and residual coal after reduction and dealkalization are discharged from a kiln head, enter semi-dry cooling equipment, are subjected to magnetic separation after being subjected to direct heat exchange and cooling by the countercurrent of atomized water, residual coke and ash are separated, and tail gas obtained after hot gas subjected to cooling and heat exchange by the semi-dry method is merged into a reburning chamber enters a waste heat power generation system. And (4) screening the residual coke and ash to obtain fine residual coke powder used as a sintered solid fuel, and returning the coarse residual coke powder to the reduction roasting process of the multi-orifice rotary kiln.
In the invention, a gas conveying pipeline is arranged in the refractory brick on the side wall of the rotary kiln, and CO is input into the gas conveying pipeline 2 The waste gas and the gas in the gas conveying pipeline absorb the heat in the rotary kiln, and the heated CO is contained 2 The waste gas is sprayed into the inner cavity of the rotary kiln through a nozzle and contains CO 2 The exhaust gas participates in the reduction of the minerals in the rotary kiln. The application provides a direct reduction rotary kiln through gas transmission pipeline's setting, has following effect: 1. feeding CO-containing gas into gas conveying pipeline 2 Exhaust gases containing CO 2 The waste gas can absorb heat on the inner wall of the rotary kiln, so that the rotary kiln is protected, and the service life of the rotary kiln is prolonged; compared with the heat preservation device arranged on the outer wall of the rotary kiln, the gas conveying pipeline is closer to the inner cavity of the rotary kiln, so that the heat of the inner wall of the rotary kiln can be dissipated, and the rotary kiln can be protected better; 2. by arranging a gas conveying pipeline in the inner wall of the rotary kiln, the gas conveying pipeline contains CO 2 The waste gas absorbs the heat emitted from the inner cavity of the rotary kiln, so that the waste heat utilization of the sensible heat of the rotary kiln is realized; 3. CO-CONTAINING IN GAS TRANSPORT PIPES 2 After absorbing heat, the waste gas is directly sprayed into the inner cavity of the rotary kiln through a nozzle at the position of the rotary kiln body and contains CO 2 The waste gas and carbon in the materials in the rotary kiln are subjected to a Boolean reaction to generate CO, and the CO is used as a reducing agent to directly reduce the materials, so that the reduction efficiency is improved; 4. by containing CO 2 Introducing waste gas, wherein carbon-material solid-solid reduction exists in the rotary kiln; at the same time, contain CO 2 The waste gas and carbon react to generate reductive CO, and the CO simultaneously reduces the materials, so that the gas-solid reduction of the materials exists in the rotary kiln, the efficiency of reducing the materials is improved, and the reduction time is shortened; 5. by injecting a CO-containing gas 2 Exhaust gas, CO 2 The carbon reacts with 1 mol of carbon to generate 2 mol of CO, the amount of the reducing agent is increased, 1 mol of the reducing agent carbon in the prior art reduces the material, and after the technical scheme of the application is adopted, 1 mol of the reducing agent carbon is changed into 2 mol of the reducing agent carbonReducing agent (CO), the same amount of material of reduction has saved the consumption of reducing agent carbon, consequently adopts the technical scheme of this application, realizes reducing the technological effect of carbon consumption.
In the present invention, the reduction of the material in the rotary kiln is in the middle section of the rotary kiln, and therefore, as a preferable aspect, the spray nozzle is provided in the middle section of the direct reduction rotary kiln. The middle section of the rotary kiln has a high temperature condition of 800-1200 ℃, and the CO contained in the rotary kiln is sprayed 2 The waste gas directly reacts with carbon in the material in a Boolean reaction, and the generated product CO directly reduces the material. If it contains CO 2 The spraying position of the waste gas is positioned at the kiln head or the kiln tail of the rotary kiln, the temperature of the kiln head or the kiln tail of the rotary kiln is relatively low, and CO is generated 2 Can not generate reduction reaction with carbon in the material; and even if the Boolean reaction occurs, the temperature at the position of the kiln head or the kiln tail is not enough, and the generated product CO can not directly reduce the materials. Through experiments, the CO is injected from the position of the kiln head or the kiln tail 2 Exhaust gases, mostly CO 2 Directly enters the flue gas in the inner cavity of the rotary kiln; very small fraction of CO 2 The product CO produced by the Buldol reaction with carbon in the materials also enters the flue gas in the inner cavity of the rotary kiln and is directly discharged from the tail of the rotary kiln along with the flue gas, so that the effect of reducing the materials cannot be achieved. Through experiments, the CO is sprayed from the position of the kiln head or the kiln tail 2 The waste gas has no obvious promotion effect on the reduction efficiency of the materials in the rotary kiln, and also has no obvious promotion effect on the metallization rate of iron in the reduced materials.
In a preferred embodiment of the present invention, the gas delivery pipe is provided with a gas bleed valve at the end thereof, and the gas bleed valve is located downstream of the nozzle. Excess CO content according to the actual process 2 The exhaust gas is discharged through a gas bleed valve. If the rotary kiln requires CO 2 Under the conditions of small waste gas quantity and high temperature in the rotary kiln, the content of CO in a gas conveying pipeline can be increased 2 The introduction amount of the exhaust gas containing CO 2 After the waste gas is heated in the gas conveying pipeline and the temperature is raised, a part of the waste gas is sprayed into the inner cavity of the rotary kiln through the nozzle, and the rest part of the waste gas contains CO 2 The exhaust gas is discharged through a gas bleed valve. This techniqueMeans not only meets the requirement of the rotary kiln on the content of CO 2 The demand of waste gas is increased by increasing the content of CO 2 The input amount of waste gas protects the rotary kiln system.
Further, the inventor finds out through experiments that the rotary kiln has a high temperature condition of 800-1200 ℃ because the rotary kiln is used for reducing the minerals, and therefore the pressure in the rotary kiln is larger. Meanwhile, the rotary kiln is a closed system, and the pressure in the rotary kiln is controlled according to the actual process requirement. The inventor finds in experiments that if the pressure in the rotary kiln is too high, the CO in the gas conveying pipeline 2 The waste gas containing CO is sprayed into the rotary kiln through a nozzle due to overlarge pressure in the rotary kiln 2 The amount of exhaust gas is very limited; the injected CO is increased along with the increase of the pressure in the rotary kiln 2 The amount of exhaust gas is reduced. When the pressure in the rotary kiln is higher, the power of the blower is simply increased to control the content of CO 2 The injection amount of exhaust gas changes less. Aiming at the technical problem, the inventor unexpectedly discovers that the gas conveying pipeline is designed into a reducing pipeline by changing the pipe diameter of the gas conveying pipeline, and the CO is conveyed into the gas conveying pipeline by a blower 2 The waste gas, heated by the heat in the rotary kiln, contains CO 2 The volume of the waste gas is increased, and simultaneously, the content of CO in the gas conveying pipeline is increased through the reducing pipeline 2 The pressure of the waste gas can obviously improve the CO content sprayed into the rotary kiln 2 The amount of exhaust gas. By means of the reducing pipeline, the CO is contained 2 The automatic pressurization of the waste gas in the gas conveying pipeline increases the content of CO in the gas conveying pipeline 2 Pressure of exhaust gas, thereby making CO contained 2 The waste gas can enter the inner cavity of the rotary kiln more easily.
Preferably, the inner diameter of the gas delivery pipe gradually decreases from the gas inlet end to the position where the nozzle is disposed. By changing the inner diameter of the gas transmission pipeline, the content of CO in the pipeline is increased 2 The pressure of the exhaust gas. The inventor further finds through experiments that when the ratio of the inner diameter of the gas conveying pipeline at the position of the nozzle to the inner diameter of the gas inlet end of the gas conveying pipeline is more than 1.5, the gas conveying pipeline contains CO along with the increase of the ratio of the inner diameters 2 The pressure of the waste gas is gradually increased and the C-containing gas enters the rotary kilnO 2 The amount of exhaust gas is also increased stepwise. When the ratio of the inner diameter of the gas conveying pipeline at the position of the nozzle to the inner diameter of the gas inlet end of the gas conveying pipeline is larger than 1:3, the ratio of the inner diameters is increased due to the fact that CO is contained 2 The self pressure of the waste gas in the gas conveying pipeline is too high, so that the CO-containing gas entering the rotary kiln 2 The amount of exhaust gas starts to decrease. When the ratio of the inner diameter of the gas conveying pipeline at the position of the nozzle to the inner diameter of the gas inlet end of the gas conveying pipeline is more than 1:4, the CO entering the rotary kiln 2 The waste gas amount is obviously reduced, which is not beneficial to containing CO 2 The exhaust gas enters the rotary kiln. Therefore, the ratio of the inner diameter of the gas conveying pipeline at the position of the nozzle to the inner diameter of the gas conveying pipeline at the gas inlet end is controlled to be 1.5-4, and preferably 1:2-3; is favorable for containing CO 2 The waste gas enters the rotary kiln to ensure that the waste gas enters the rotary kiln and contains CO 2 The amount of exhaust gas, thereby ensuring CO content 2 The exhaust gas participates in the reduction of the minerals in the rotary kiln.
When the pressure in the rotary kiln is too high, the inventor finds that the pressure-boosting anti-backflow fin arranged on the inner wall of the gas conveying pipeline can increase the content of CO in the gas conveying pipeline 2 The pressure of the exhaust gas. By means of pressurized anti-reflux fin arrangement, containing CO 2 The technical effect of automatic pressurization of the waste gas in the gas conveying pipeline is achieved. Containing CO 2 The waste gas passes through a gas conveying pipeline provided with a pressurizing backflow-preventing fin and contains CO 2 The heated volume of the waste gas is increased, and the CO content is further improved by a pressurizing anti-backflow fin 2 Pressure of exhaust gas so as to contain CO 2 The waste gas enters the inner cavity of the rotary kiln more smoothly.
The inventor further experiments show that as the included angle between the pressurizing backflow-preventing fin and the inner wall of the gas conveying pipeline is increased, the CO in the gas conveying pipeline 2 The pressure of the waste gas is gradually increased, and the CO-containing gas enters the rotary kiln under the condition of the same blower power and rotary kiln 2 The amount of exhaust gas gradually increases. However, when the angle between the pressurized backflow-preventing fin and the inner wall of the gas conveying pipeline is more than 60 degrees, the CO is contained 2 The self pressure of the waste gas in the gas conveying pipeline is too high, so that the CO-containing gas entering the rotary kiln 2 The amount of exhaust gas starts to decrease. When the pressure boost prevents the backflow fin and gas delivery pipeWhen the included angle of the inner wall is more than 80 degrees, the CO in the rotary kiln 2 The waste gas amount is obviously reduced, which is not beneficial to containing CO 2 The exhaust gas enters the rotary kiln. Therefore, the included angle between the pressurizing backflow-preventing fin and the inner wall of the gas conveying pipeline is controlled to be 20-80 degrees, and preferably 30-60 degrees; is favorable for containing CO 2 Waste gas enters the rotary kiln to ensure that the waste gas enters the rotary kiln and contains CO 2 The amount of exhaust gas, and thus the CO content 2 The exhaust gas participates in the reduction of the minerals in the rotary kiln.
In the invention, the section of the pressurizing anti-backflow fin is in a splayed structure, and the tail end of the pressurizing anti-backflow fin 3 in the splayed structure is connected with the inner wall of the gas conveying pipeline. That is, the end of the pressurizing anti-backflow fin with the larger opening of the splayed structure is connected with the inner wall of the gas conveying pipeline and is positioned at the upstream of the gas conveying pipeline (containing CO) 2 Upstream of the exhaust gas flow direction); the end with the smaller opening of the pressurizing backflow-preventing fin of the splayed structure is positioned in the gas conveying pipeline, is separated from the inside of the gas conveying pipeline and is positioned at the downstream of the gas conveying pipeline. (as shown in FIG. 4)
In a preferred embodiment of the present invention, the gas transport pipe is a variable diameter pipe, and the inner diameter of the gas transport pipe gradually decreases from the gas inlet end to the installation position of the nozzle, and gradually increases from the installation position of the nozzle to the position of the gas diffusing valve. By the technical means, the inner diameter of the gas conveying pipeline is gradually reduced from the gas inlet end to the nozzle position, so that the content of CO in the gas conveying pipeline is increased 2 The pressure of the exhaust gas is favorable for containing CO 2 Waste gas enters the inner cavity of the rotary kiln; from the position of the nozzle to the position of the gas diffusion valve, the inner diameter of the gas conveying pipeline is gradually increased, and the gas can be controlled to enter the inner cavity of the rotary kiln to contain CO through the control of the gas diffusion valve 2 The amount of exhaust gas. When the rotary kiln needs to contain CO 2 When the exhaust gas is reduced, the inner diameter of the gas delivery pipe gradually increases from the nozzle position to the gas diffusion valve position through the gas diffusion valve, and the gas delivery pipe contains CO 2 The exhaust gas is preferentially discharged from the gas bleeding valve. Therefore, the CO content can be controlled only by controlling the opening of the gas diffusion valve 2 Discharge of exhaust gas, and control thereofMaking CO in rotary kiln 2 The amount of exhaust gas.
In the preferable scheme of the invention, the pressurizing backflow-preventing fin is arranged inside the gas conveying pipeline. And a pressurizing anti-backflow fin is arranged in the gas conveying pipeline from the gas inlet end to the setting position of the nozzle, and the pressurizing anti-backflow fin is not arranged in the gas conveying pipeline from the setting position of the nozzle to the position of the gas diffusing valve. By arranging the pressurizing anti-backflow fin, the inner diameter of the gas conveying pipeline is gradually reduced from the gas inlet end to the nozzle position, so that the content of CO in the gas conveying pipeline is increased 2 The pressure of the exhaust gas is favorable for containing CO 2 Waste gas enters the inner cavity of the rotary kiln; from the nozzle position to the gas diffusion valve position, without obstruction of the pressurized anti-backflow fins, the position containing CO 2 The pressure of the waste gas is low, which is beneficial to containing CO 2 And (4) discharging the waste gas. The control of the gas diffusion valve can control the CO in the inner cavity of the rotary kiln 2 The amount of exhaust gas. When the rotary kiln needs to contain CO 2 When the waste gas is reduced, the gas delivery pipeline is not provided with a pressurizing backflow-preventing fin from the position of the nozzle to the position of the gas diffusing valve through the gas diffusing valve, and the CO is contained 2 The exhaust gas is preferentially discharged from the gas bleeding valve. Therefore, the CO content can be controlled only by controlling the opening of the gas diffusion valve 2 The emission of waste gas is controlled to enter the rotary kiln to contain CO 2 The amount of exhaust gas.
In order to solve another technical problem in the prior art, the temperature measurement of the rotary kiln is always a technical problem in the field because the rotary kiln is in a high-temperature environment and is in a rotating state, and materials are contacted with and rub the inner wall of the rotary kiln at any time. According to the invention, the gas conveying pipeline is arranged in the side wall of the rotary kiln, the temperature measuring element is arranged on the inner wall of the gas conveying pipeline, and the temperature of the gas in the gas conveying pipeline is detected by the temperature measuring element, so that the temperature in the rotary kiln at the corresponding position can be deduced according to the actual working experience. Because the gas in the gas conveying pipeline is heated by the heat in the rotary kiln, the temperature in the rotary kiln can be reversely deduced through the temperature of the gas steam. With temperature element setting at the gas transmission pipeline inner wall, compare in the rotary kiln in the wearing and tearing of solid-state material, the gas state that flows in the gas transmission pipeline, gaseous wearing and tearing to temperature element are far less, consequently, solved among the prior art because the material is to temperature element wearing and tearing, be not convenient for detect the technical problem of temperature in the rotary kiln.
The invention provides a calcification reduction dealkalization method for vanadium extraction tailings, the diameter of a green pellet is 1-20mm (preferably 2-10mm, more preferably 3-8 mm), the green pellet consolidation mode is carbonation consolidation, compared with common carbonation low-temperature consolidation, the green pellet consolidated by adopting a composite low-temperature curing agent has the characteristics of faster and more uniform carbonation reaction, higher pellet strength and higher production efficiency.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial technical effects:
1. the composite low-temperature curing agent is added into the composite pellets, and can release CO in the low-temperature drying and consolidation process 2 And H 2 O, and can obviously improve the carbonation consolidation efficiency and the dry consolidation ball strength;
2. the invention adopts a carbonation consolidation method of hot air drying and microwave drying consolidation aiming at the drying consolidation of the composite pellets, and the composite low-temperature curing agent in the pellets is uniformly decomposed and converted into CO under the action of microwaves 2 And H 2 O, the problem that the reaction of the outer layer of the pellet and the inner substance of the pellet is not synchronous due to the traditional outside-in heat conduction mode is avoided, and high-strength guarantee is provided for the pellet;
3. the structure of the existing rotary kiln is upgraded and modified, a gas conveying pipeline is embedded in a refractory material, and the gas in the gas conveying pipeline realizes the high-efficiency recovery of the unorganized heat dissipation of the kiln wall; meanwhile, the rotary kiln is protected.
4. The gas conveyed to the rotary kiln through the gas conveying pipeline and the fuel in the rotary kiln generate a Boolean reaction to generate a large amount of reducing gas CO; the reduction reaction speed is improved, low-temperature rapid reduction is realized, and the carbon consumption of unit materials for reduction is reduced.
5. The kiln body air inlet rotary kiln adopted by the invention can effectively adjust the temperature field in the kiln through the multiple spray holes of the kiln body, reduce the temperature of the high-temperature area by supplying air to the high-temperature area, prevent the material from melting and ring formation due to overhigh temperature, improve the combustion efficiency of reducing gas in the kiln by supplying air to the kiln from the middle section to the tail section of the kiln, increase the gas temperature in the tail direction of the kiln, effectively prolong the area of the high-temperature area and provide a longer-time high-temperature roasting environment for material reduction.
6. The invention adopts atomized water as cooling medium to carry out semidry cooling on the reducing material, has good cooling effect, and reforms the atomized water by utilizing the characteristics of high temperature and high carbon residue of the reducing material to obtain CO and H containing reducing gases 2 The gas improves the resource utilization degree of the process.
Drawings
FIG. 1 is a process flow diagram of a calcification reduction dealkalization method of vanadium extraction tailings of the invention;
FIG. 2 is an optimized process flow diagram of the calcification reduction dealkalization method of the vanadium extraction tailings of the invention;
FIG. 3 is a schematic view of the structure of a direct reduction rotary kiln of the present invention;
FIG. 4 is a schematic structural diagram of a gas transmission pipeline in a direct reduction rotary kiln according to the present invention, wherein the gas transmission pipeline is a variable diameter pipeline;
FIG. 5 is a schematic structural view of a pressurized anti-backflow fin provided in a gas delivery pipe in the direct reduction rotary kiln of the present invention;
fig. 6 is a process diagram of the direct reduction rotary kiln of the invention for mineral reduction.
Reference numerals are as follows:
1: a direct reduction rotary kiln; 101: a kiln head; 102: a kiln body; 103: a kiln tail; 10101: burning a nozzle; l1: a gas delivery conduit; 10201: a nozzle; 2: a gas bleeding valve; 3: pressurizing anti-backflow fins; 4: a temperature measuring element.
Detailed Description
The technical solution of the present invention is illustrated below, and the claimed scope of the present invention includes, but is not limited to, the following examples.
Example 1
A calcification reduction dealkalization method of vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and the composite low-temperature curing agent, and pelletizing to obtain green pellets;
2) Carrying out hot air drying and microwave consolidation on the green pellets in sequence to obtain consolidated pellets;
3) Conveying the consolidated pellets to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material.
The composite low-temperature curing agent is obtained by mixing calcium hydroxide and starch according to a weight ratio of 1:1, and the mixing weight ratio of the vanadium extraction tailings to the composite low-temperature curing agent is 1. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm.
Example 2
A calcification reduction dealkalization method of vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and the composite low-temperature curing agent, and pelletizing to obtain green pellets;
2) Carrying out hot air drying and microwave consolidation on the green pellets in sequence to obtain consolidated pellets;
3) Mixing the consolidated pellets and the coke powder, conveying the mixture to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material. Wherein the tail gas after desulfurization treatment contains CO 2 Exhaust gas will contain CO 2 The waste gas is divided into two parts, one part contains CO 2 Waste gas is input and conveyed to the rotary kiln from the position of the middle kiln body of the rotary kiln; a part containing CO 2 The exhaust gas is sent to the microwave consolidation step, and the gas discharged from the microwave consolidation step is sent to the hot air drying step.
The composite low-temperature curing agent is obtained by mixing calcium hydroxide and starch according to a weight ratio of 1:1, and the mixing weight ratio of the vanadium extraction tailings to the composite low-temperature curing agent is 1. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm. The weight ratio of the consolidated pellets to the coke powder is 1.
Example 3
Example 2 was repeated except that the cooling described in step 3) was performed by semi-dry cooling, specifically:
301 Passing the water through an atomization system to obtain atomized water;
302 Conveying the reducing material into a semi-dry cooling device, and introducing atomized water into the semi-dry cooling device; cooling the reduced material with atomized water, absorbing heat in the reduced material with atomized water, and water-gas reaction of atomized water and residual carbon in the reduced material to obtain CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
Example 4
Example 3 was repeated except that the tail gas after desulfurization was CO-containing 2 Exhaust gas will contain CO 2 The waste gas is divided into three parts, and one part contains CO 2 Conveying the waste gas to a rotary kiln; a part containing CO 2 Conveying the waste gas to a microwave consolidation step, and conveying the gas discharged from the microwave consolidation step to a hot air drying step; the remaining CO-containing 2 Conveying the waste gas to an atomization device, wherein CO is dissolved in atomized water 2 (ii) a Dissolved with CO 2 The atomized water is reformed by a semidry cooling device, and CO is obtained 2 Performing a Boolean reaction with the carbon residue in the reduced material, and performing a water gas reaction with the atomized water to obtain a product containing CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
Example 5
The example 4 is repeated, except that the screening in the step 3) is magnetic separation, and the iron-vanadium raw material and the carbon residue are obtained through the magnetic separation. And screening the residual carbon to obtain fine-grain coke powder and coarse-grain coke powder, wherein the fine-grain coke powder is used as a sintering ingredient, and the coarse-grain coke powder is conveyed to the rotary kiln. The iron vanadium raw material is conveyed to a blast furnace. The alkali-containing dust is obtained through the first dust removal treatment and the second dust removal treatment. The waste heat utilization is specifically waste heat power generation.
Example 6
Example 5 is repeated except that the composite low-temperature curing agent is obtained by mixing calcium oxide and coal tar according to a weight ratio of 1:1, and the mixing weight ratio of the vanadium extraction tailings to the composite low-temperature curing agent is 1. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm.
Example 7
Example 5 was repeated except that the composite low temperature curing agent was obtained by mixing calcium carbonate and molasses at a weight ratio of 1:1, and the mixing weight ratio of the vanadium extraction tailings and the composite low temperature curing agent was 1. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm.
Example 8
Example 5 was repeated, except that in step 2), the microwave consolidation step was carried out with a CO-containing stream 2 And steam containing CO 2 And the gas of the water vapor is conveyed to the microwave consolidation step, and the gas discharged from the microwave consolidation step is conveyed to the hot air drying step. Containing CO 2 The gas with steam is added with steam and CO 2 Hot air of (containing CO) 2 And CO in the gas of steam 2 Concentration of 30% and CO content 2 And the humidity of the gas of water vapor is 30g/m 3 。
Example 9
Example 5 was repeated, except that in step 2), CO-containing gas was introduced into the microwave consolidation step 2 And steam containing CO 2 And the gas of the water vapor is conveyed to the microwave consolidation step, and the gas discharged from the microwave consolidation step is conveyed to the hot air drying step. Containing CO 2 The gas mixed with water vapor is hot tail gas after the combustion of blast furnace gas and contains CO 2 And CO in the gas of steam 2 35% concentration of CO 2 The humidity of the gas with water vapor is 25g/m 3 。
Example 9
Example 5 was repeated except that in step 3), the weight ratio of the consolidated pellets to the coke powder was 1. Coal is sprayed from the kiln head of the rotary kiln in the reduction roasting process. The weight ratio of the injected coal to the consolidated pellets was 0.3.
Example 10
Example 5 was repeated except that the hot air drying process was two-stage hot air drying including a hot air drying stage I and a hot air drying stage II. The microwave consolidation process is two-stage microwave consolidation and comprises a microwave consolidation section I and a microwave consolidation section II. The green pellets sequentially pass through a hot air drying section I, a hot air drying section II, a microwave consolidation section I and a microwave consolidation section II to obtain consolidated pellets.
Example 11
Example 10 was repeated except that the drying temperature in the hot air drying stage I was 80 ℃ and the drying time was 10min. The drying temperature of the hot air drying section II is 200 ℃, and the drying time is 10min. After the hot air drying process, the mass content of water in the pellets is 4%.
The temperature of the microwave consolidation stage I is 300 ℃, and the pellet retention time is 10min. The temperature of the microwave consolidation II section is 450 ℃, and the pellet retention time is 10min. The microwave power density in the microwave consolidation procedure is 25kw/m 3 。
Example 12
Example 5 was repeated except that the calcination reduction was carried out in step 3 using a direct reduction rotary kiln. The direct reduction rotary kiln 1 comprises a kiln head 101, a kiln body 102 and a kiln tail 103; a burner 10101 is arranged at the position of the kiln head 101; the direct reduction rotary kiln 1 is of a cylindrical structure, and the side wall of a kiln body 102 of the direct reduction rotary kiln 1 is formed by stacking refractory bricks; a gas conveying pipeline L1 is arranged in a refractory brick on the side wall of the kiln body 102; a nozzle 10201 is arranged on the inner side wall of the kiln body 102; the nozzle 10201 is communicated with the gas delivery pipeline L1 and the inner chamber of the rotary kiln 1; the nozzle 10201 is provided at a middle kiln body position of the rotary kiln 1.
Example 13
Example 12 was repeated except that the end of the gas delivery pipe L1 was provided with a gas release valve 2 and that the gas release valve 2 was located downstream of the nozzle 10201.
Example 14
Example 13 was repeated except that the gas transmission line L1 was a variable diameter line; the inner diameter of the gas delivery pipe L1 gradually becomes smaller from the gas inlet end to the position where the nozzle 10201 is disposed; the inner diameter of the gas delivery pipe L1 gradually becomes larger from the position where the nozzle 10201 is disposed to the position of the gas release valve 2; the ratio of the inner diameter of the gas delivery conduit at the nozzle location to the inner diameter of the gas delivery conduit at the gas inlet end is 1:2.
Example 15
Example 13 was repeated except that the inner wall of the gas conveying pipe L1 was provided with a pressurizing anti-reflux fin 3; the section of the pressurizing backflow-preventing fin 3 is of a splayed structure, and the tail end of the pressurizing backflow-preventing fin 3 of the splayed structure is connected with the inner wall of the gas conveying pipeline L1 and is located at the upstream. The included angle between the pressurizing backflow-preventing fin and the inner wall of the water vapor pipeline is 30 degrees.
Comparative example 1
A calcification reduction dealkalization method of vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and calcium hydroxide, and pelletizing to obtain green pellets;
2) Drying and consolidating the green pellets by hot air in sequence to obtain consolidated pellets;
3) Conveying the consolidated pellets to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material.
Wherein the mixing weight ratio of the vanadium extraction tailings to the calcium hydroxide is 1. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm.
Comparative example 2
A calcification reduction dealkalization method for vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and calcium hydroxide, and pelletizing to obtain green pellets;
2) Carrying out hot air drying and microwave consolidation on the green pellets in sequence to obtain consolidated pellets;
3) Conveying the consolidated pellets to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material.
Wherein the mixing weight ratio of the vanadium extraction tailings to the calcium hydroxide is 1. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm.
Comparative example 3
A calcification reduction dealkalization method of vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and the composite low-temperature curing agent, and pelletizing to obtain green pellets;
2) Drying and consolidating the green pellets by hot air in sequence to obtain consolidated pellets;
3) Conveying the consolidated pellets to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material.
The composite low-temperature curing agent is obtained by mixing calcium hydroxide and starch according to a weight ratio of 1:1, and the mixing weight ratio of the vanadium extraction tailings to the composite low-temperature curing agent is 1.5. The green pellets had a water content of 10% by weight and an average particle diameter of 5mm.
The technical scheme of the examples 1, 2, 3, 4, 11, 12, 14 and 15 and the technical scheme of the comparative examples 1, 2 and 3 are adopted for effect verification, the adopted vanadium extraction tailings are all sodium-modified vanadium extraction tailings of the same batch, and the starch is industrial starch of the same batch. The coking coal is the same batch of raw material. The calcium hydroxide is obtained by digesting the same batch of quicklime through the same process. The mixing equipment who adopts, the balling disc, drying system (being used for hot air drying) of chain grate, microwave system, the rotary kiln of embodiment 1, 2, 3, 4, 11, comparative example 1, 2, 3 is same equipment, carries out experiment and effect verification, and the result is as follows:
Figure BDA0003986925500000201
Figure BDA0003986925500000211
in the invention, the compressive strength of the consolidated pellets is detected according to the GB/T14201-93 standard. The falling strength of the consolidated pellets is detected according to the GB/T14201-93 standard.
The content of alkali metal in the iron vanadium raw material is sampled and analyzed chemically in a laboratory to obtain an accurate result.
The metallization rate of the iron metallization rate in the iron-vanadium raw material refers to: in the whole reducing material (slag phase), the elementary substance iron accounts for the weight percentage of the total iron element components.
The vanadium metallization rate in the iron-vanadium raw material refers to the weight percentage of the elementary vanadium in the whole reduction material (slag phase) in the total vanadium element component.

Claims (11)

1. A calcification reduction dealkalization method of vanadium extraction tailings comprises the following steps:
1) Uniformly mixing the vanadium extraction tailings and the composite low-temperature curing agent, and pelletizing to obtain green pellets;
2) Carrying out hot air drying and microwave consolidation on the green pellets in sequence to obtain consolidated pellets;
3) Conveying the consolidated pellets to a rotary kiln for reduction roasting, and sequentially carrying out primary dust removal treatment, reburning reaction, waste heat utilization, secondary dust removal treatment and desulfurization treatment on dust-containing tail gas discharged from the rotary kiln; and (3) cooling and screening the reduced material obtained by reduction roasting in a rotary kiln to obtain the iron-vanadium raw material.
2. The calcification reduction dealkalization method for the vanadium extraction tailings according to claim 1, which is characterized in that: the tail gas subjected to desulfurization treatment in the step 3) contains CO 2 Exhaust gas will contain CO 2 The waste gas is divided into two parts, one part contains CO 2 Conveying the waste gas to a rotary kiln; preferably, the CO-containing feed to the rotary kiln 2 Waste gas from the middle of the rotary kilnInputting the position of the kiln body;
a part containing CO 2 The exhaust gas is sent to the microwave consolidation step, and the gas discharged from the microwave consolidation step is sent to the hot air drying step.
3. The method for calcification reduction dealkalization of vanadium extraction tailings as claimed in claim 2, wherein: the cooling in the step 3) adopts a semidry method, and specifically comprises the following steps:
301 Passing the water through an atomization system to obtain atomized water;
302 Conveying the reducing material into a semi-dry cooling device, and introducing atomized water into the semi-dry cooling device; cooling the reduced material with atomized water, absorbing heat in the reduced material with atomized water, and water-gas reaction of atomized water and residual carbon in the reduced material to obtain CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets;
preferably, the remaining CO is 2 The waste gas is conveyed to an atomization device, and CO is dissolved in the atomized water 2 (ii) a Dissolved with CO 2 The atomized water is reformed by a semidry cooling device, and CO is obtained 2 Performing a Boolean reaction with the carbon residue in the reduced material, and performing a water gas reaction with the atomized water to obtain a product containing CO and H 2 Will contain CO and H 2 The hot gas is conveyed to a waste heat utilization process for waste heat utilization and/or contains CO and H 2 The hot gas is conveyed to the rotary kiln for reduction of the consolidated pellets.
4. The method for calcification reduction dealkalization of vanadium extraction tailings according to any one of claims 1 to 3, wherein: the screening in the step 3) is magnetic separation, and iron and vanadium raw materials and residual carbon are obtained through magnetic separation; and/or
The waste heat utilization is specifically waste heat power generation;
preferably, screening the residual carbon to obtain fine-particle-size coke powder and coarse-particle-size coke powder, wherein the fine-particle-size coke powder is used as a sintering ingredient, and the coarse-particle-size coke powder is conveyed to the rotary kiln; conveying the iron-vanadium raw material to a blast furnace; the alkali-containing dust is obtained through the first dust removal treatment and the second dust removal treatment.
5. The method for calcification reduction dealkalization of vanadium extraction tailings according to any one of claims 1 to 4, wherein: the composite low-temperature curing agent in the step 1) is obtained by uniformly mixing one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride and calcium sulfate with one or more of starch, coal tar and molasses; and/or
The mixing weight ratio of the vanadium extraction tailings to the composite low-temperature curing agent is 1.1-1, preferably 1.2-0.8; the green ball has a water content of 5 to 20% by weight, preferably 8 to 12% by weight; the green pellets have a particle size of 2 to 12mm, preferably 3 to 8mm.
6. The method for calcification reduction dealkalization of vanadium extraction tailings according to any one of claims 1 to 5, wherein: in the step 2), CO is introduced in the microwave consolidation procedure 2 And steam, containing CO 2 And steam, and the gas discharged from the microwave consolidation step is conveyed to a hot air drying step;
preferably, it contains CO 2 The gas with steam is added with steam and CO 2 Any one of hot air, blast furnace gas, coke oven gas or hot tail gas after converter gas combustion, direct reduction hot tail gas and lime kiln hot tail gas; containing CO 2 CO in gas with water vapor 2 The concentration is 10 to 50 percent, and preferably 20 to 40 percent; containing CO 2 The humidity of the gas with water vapor is 10g/m 3 ～100g/m 3 Preferably 20g/m 3 ～50g/m 3 。
7. The method for calcification reduction dealkalization of vanadium extraction tailings according to any one of claims 1 to 6, wherein: in the step 3), the consolidated pellets and the coke powder are mixed and then are conveyed to a rotary kiln for reduction roasting; the weight ratio of the consolidated pellets to the coke powder is 1;
preferably, coal is sprayed from the kiln head of the rotary kiln in the reduction roasting process; the weight ratio of the injected coal to the consolidated pellets is 0.1-1:1, preferably 0.2-0.5.
8. The method for calcification reduction dealkalization of vanadium extraction tailings according to any one of claims 1 to 7, wherein: the hot air drying process is two-stage hot air drying and comprises a hot air drying I section and a hot air drying II section; the microwave consolidation process is two-stage microwave consolidation and comprises a microwave consolidation I section and a microwave consolidation II section; the green pellets sequentially pass through a hot air drying section I, a hot air drying section II, a microwave consolidation section I and a microwave consolidation section II to obtain consolidated pellets;
preferably, the drying temperature of the hot air drying I section is 60-100 ℃, and the drying time is 2-20 min; the drying temperature of the hot air drying section II is 100-250 ℃, and the drying time is 2-20 min; after the hot air drying process, the mass content of water in the pellets is 2-8%, preferably 4-6%;
the temperature of the microwave consolidation I section is 250-350 ℃, and the pellet retention time is 2-20 min; the temperature of the microwave consolidation II section is 350-500 ℃, and the pellet retention time is 2-20 min; the microwave power density in the microwave consolidation procedure is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
9. The method for calcification reduction dealkalization of vanadium extraction tailings according to any one of claims 1 to 8, wherein: the rotary kiln is a direct reduction rotary kiln (1), and the direct reduction rotary kiln (1) comprises a kiln head (101), a kiln body (102) and a kiln tail (103); a burner (10101) is arranged at the position of the kiln head (101); the direct reduction rotary kiln (1) is of a cylindrical structure, and the side wall of a kiln body (102) of the direct reduction rotary kiln (1) is formed by stacking refractory bricks; a gas conveying pipeline (L1) is arranged in a refractory brick on the side wall of the kiln body (102); a nozzle (10201) is arranged on the inner side wall of the kiln body (102); the nozzle (10201) is communicated with the gas delivery pipeline (L1) and the inner chamber of the rotary kiln (1); the nozzle (10201) is arranged at the middle kiln body position of the rotary kiln (1).
10. The calcification reduction dealkalization method for the vanadium extraction tailings according to claim 9, which is characterized in that: the end of the gas delivery pipe (L1) is provided with a gas blow-off valve (2), and the gas blow-off valve (2) is located downstream of the nozzle (10201).
11. The method for calcification reduction dealkalization of vanadium extraction tailings as claimed in claim 10, wherein: the gas conveying pipeline (L1) is a reducing pipeline; the inner diameter of the gas delivery pipe (L1) is gradually reduced from the gas inlet end to the arrangement position of the nozzle (10201); the inner diameter of the gas delivery pipe (L1) gradually increases from the setting position of the nozzle (10201) to the position of the gas diffusion valve (2); and/or
A pressurizing anti-backflow fin (3) is arranged on the inner wall of the gas conveying pipeline (L1); the section of the pressurizing backflow-preventing fin (3) is of a splayed structure, and the tail end of the pressurizing backflow-preventing fin (3) of the splayed structure is connected with the inner wall of the gas conveying pipeline (L1) and is located at the upstream.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117230306A (en) * 2023-11-14 2023-12-15 北京蒂本斯工程技术有限公司 Method and system for treating vanadium extraction waste slag by adopting side-blown furnace melting separation method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117230306A (en) * 2023-11-14 2023-12-15 北京蒂本斯工程技术有限公司 Method and system for treating vanadium extraction waste slag by adopting side-blown furnace melting separation method
CN117230306B (en) * 2023-11-14 2024-02-09 北京蒂本斯工程技术有限公司 Method and system for treating vanadium extraction waste slag by adopting side-blown furnace melting separation method

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