CN112941324A

CN112941324A - Novel process for comprehensively utilizing resources containing heavy metal hazardous wastes

Info

Publication number: CN112941324A
Application number: CN202110120403.XA
Authority: CN
Inventors: 赵江晨; 赵乐陶
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-01-28
Filing date: 2021-01-28
Publication date: 2021-06-11

Abstract

The application discloses a novel resource comprehensive utilization process for hazardous waste containing heavy metals. The process comprises the following steps of S1: pretreating and classifying and storing the hazardous waste containing the heavy metals; s2: adding water into hazardous waste containing heavy metals, coke powder, bentonite, quartz sand or lime to mix to form a mixture; s3: pressing the mixture into balls and drying; s4: the pellets enter the rotary kiln after being screened, and the powder returns to the step S2; s5: reducing the operation temperature of the rotary kiln, and treating the flue gas to produce primary ash containing zinc and lead and zinc hypoxide; s6: the kiln slag is thermally sent to a melting electric furnace for smelting, the residual zinc and lead are secondarily reduced and volatilized to enter smoke, iron, nickel, chromium and manganese are reduced to produce molten iron, and the slag is thermally sent to the step S7 for tempering; s7: adding solid waste into a quenching and tempering electric furnace to quench and temper the molten slag; s8: and (4) hardening and tempering the qualified slag to produce the slag wool board. The method solves the technical problems that the residue and the waste catalyst of the Wilz kiln are difficult to thoroughly realize harmless and recycling, and the Wilz kiln is easy to ring.

Description

Novel process for comprehensively utilizing resources containing heavy metal hazardous wastes

Technical Field

The application relates to the technical field of comprehensive utilization of industrial solid waste resources, mainly comprehensively utilizes resources of heavy metal-containing dust, sludge, waste residues and waste catalysts, and particularly relates to a novel process for comprehensively utilizing heavy metal-containing hazardous waste resources such as zinc/lead/nickel/chromium/manganese.

Background

The zinc-containing dust, sludge and waste residue are various and large in quantity, belong to dangerous waste, mainly comprise zinc leaching residues, electric furnace ash, blast furnace cloth bag ash, lead smelting blast furnace slag, zinc-containing electroplating sludge, hot galvanizing dedusting ash and the like, and are usually accompanied with lead and iron besides high zinc. At present, the process for recovering zinc metal from zinc-containing wastes at home and abroad is mainly a rotary kiln reduction volatilization process, also called a Wilz process, and a rotary kiln adopting the Wilz process is called a Wilz kiln.

The waste catalyst has various types and small quantity, and belongs to dangerous waste. Because the high-grade metal ore contains high content of noble metal (such as platinum and rhodium) or other valuable metals (such as Zn, Ni, Cr, Mo, V, Fe and the like), and is even far higher than the content of corresponding components in certain lean ores, the high-grade metal ore becomes an important raw material for comprehensively utilizing nonferrous metals and oxides thereof. The waste catalyst can be divided into: non-carrier type, diatomaceous earth carrier, Al₂O₃MgO carrier and Cr₂O₃Carrier, SiO₂·Al₂O₃The carrier and the active carrier are in six types. The components are as follows: nickel catalysts, zinc catalysts, nickel zinc catalysts, chromium aluminum catalysts, iron-based catalysts, and the like.

Specifically, the zinc-containing hazardous wastes, such as zinc/lead/nickel/chromium/manganese, and the like, mainly comprise the zinc-containing hazardous wastes and the waste catalysts containing various carriers of nickel, zinc, chromium and iron.

The difference of the existing Wilz technology in China is large, and the method is mainly characterized in that: lime or silica sand is not generally added in the ingredients; in the flue gas treatment process, after large-particle smoke dust is removed by gravity dust removal, the flue gas passes through a surface cooler and a bag dust collector to recover secondary zinc oxide, and the flue gas after the secondary zinc oxide is obtained is uniformly discharged after passing through a tail gas treatment system; the flue gas treatment system is relatively simple and generally does not consider the removal of dioxins. The slag is generally quenched with water and sold as a cement raw material. The difference between the foreign Wilz process and the domestic process is large, silica sand or lime is generally added during the material preparation, and the alkalinity of the slag is adjusted within a certain range; after the flue gas comes out from the gravity settling chamber, the flue gas is subjected to flue gas quenching to avoid a dioxin synthesis temperature window, the flue gas after secondary zinc oxide recovery is subjected to standard-reaching emission after a tail gas treatment system, and more importantly, the removal of dioxin, heavy metals such as mercury and cadmium is performed. At present, the Wilz process at home and abroad still has some common defects, which troubles the development of the industry, and the defects are as follows: (1) from the resource and environmental point of view, the effects of harmlessness, reduction and reclamation are not obvious. For example, the amount of slag is large, the amount of Fe in the slag is high (about 40%), and still contains some heavy metals Zn (about 2%), Pb (about 0.5%). Because the iron content is relatively low and the zinc-lead impurities are still high, the sintering material which is difficult to use for iron making is currently mainly used as a cement iron-containing raw material and is still in a low-value utilization stage. (2) Ring formation in rotary kilns is still unavoidable. In the raw material pretreatment link, a mode of simply mixing materials instead of solidifying and pelletizing is generally adopted, so that the intensity of materials entering a kiln is low, the powder quantity is large, and the materials are easy to adhere to the wall of the kiln to reduce the surface energy of the materials. In addition, local overheating is easy to occur in the high-temperature area of the rotary kiln, and low-melting-point powder is melted to form a ring. The ring formation can seriously affect the production efficiency, and can cause the kiln shutdown in serious cases. (3) Sensible heat of the kiln slag can not be recovered. The red hot kiln slag has a temperature as high as about 900 ℃ and contains certain sensible heat. The water quenching method not only wastes the sensible heat, but also consumes certain water resources.

At present, the resource utilization methods of the waste catalyst mainly comprise a pyrogenic process, a wet process and a pyrogenic process-wet process combined method. The application of the fire method is less in China, and the wet method is mainly used. Since the waste catalyst is a hazardous waste, a large amount of waste slag which is difficult to treat and is formed after wet treatment is still a hazardous waste, the application of the waste catalyst is limited, and the waste catalyst is mainly used for extracting noble metals at present. The fire process mainly comprises a smelting method, a chlorination method and an incineration method. The smelting method is generally applied, the metal recovery rate is high, but the requirement on equipment is high, the method has obvious advantages only when reaching a certain scale, necessary pretreatment is carried out on the waste catalyst, and proper flux, trapping agent, smelting equipment and operation system are selected. The chlorination method has the advantages of low energy consumption, simple and convenient operation, low reagent consumption and high Rh recovery rate, but Cl₂Toxic and severely corrosive to equipment; the burning method has short flow, high efficiency and low treatment cost, and is suitable for the single carbon carrier waste catalyst.

In summary, the traditional process has certain limitations, the invention adopts multiple processes to combine, develops advantages and avoids disadvantages, and thoroughly solves the technical problems of common defects of the Wilz process at home and abroad, high requirements on waste catalyst smelting conditions and the like.

Disclosure of Invention

The application mainly aims to provide a novel process for comprehensively utilizing hazardous waste resources containing heavy metals, so as to thoroughly solve the defects of the Wilz process, solve the technical problems of environmental pollution and resource waste caused by high smelting condition requirements of waste catalysts and incapability of better utilizing hazardous waste containing heavy metals. The hazardous waste containing heavy metals comprises zinc-containing dust, sludge and waste residues, and catalysts containing various carriers of nickel, zinc, chromium and iron.

In order to achieve the above object, according to one aspect of the present application, there is provided a new process for comprehensive utilization of hazardous waste resources containing heavy metals, comprising the steps of:

s1: pretreating and storing hazardous heavy metal wastes containing zinc/lead/nickel/chromium/manganese and the like according to components in a classified manner, wherein the massive materials need to be crushed into powder of 1mm or less, and the powder and sludge can directly enter the step S2;

s2: adding the hazardous waste containing the heavy metals, bentonite, coke powder and quartz sand as material components into a mixer according to a ratio calculated in advance, and adding water for mixing to obtain a mixture;

s3: pressing the obtained mixture into pellets by a ball press machine, drying the pellets, and entering step S4 when the moisture content of the pellets is less than 3%; the bentonite is used as a binder, so that the high-temperature strength of the pellets is increased, and the pellets are not easy to break in the rotary kiln to generate powder;

s4: screening the pellets, feeding the screened pellets into the rotary kiln in the step S5, and returning the screened powder to the step S2 for re-mixing; the powder is a material basis of the ring formation of the rotary kiln, and the powder is completely avoided;

s5: reacting the screened pellets in a rotary kiln to reduce the highest operation temperature of a reduction zone in the kiln, and discharging flue gas generated by the rotary kiln after sequentially passing through gravity settling, flue gas quenching, cloth bag filtering and a tail gas treatment system, wherein primary ash containing zinc and lead obtained after the gravity settling is used as a zinc-containing raw material and returns to the step S1, and secondary zinc oxide collected by the cloth bag filtering belongs to a product; discharging the red hot kiln slag from the kiln head, and performing treatment in step S6;

s6: discharging the kiln slag generated in the step S5 to a melting electric furnace for smelting, adding quartz sand or lime in the electrified smelting process to adjust the alkalinity of the slag to 1.2-1.5, ensuring that the ratio of a carbonaceous reducing agent is not higher than 8%, regulating and controlling the furnace temperature, secondarily reducing and volatilizing heavy metals such as zinc, lead and the like remained in the kiln slag and discharging the heavy metals into flue gas, fully reducing iron, nickel, manganese and chromium in the kiln slag and generating molten iron, feeding all the rest substances in the melting electric furnace into molten slag, carrying out ingot casting on the molten iron after separating the molten slag and the iron to generate an alloy iron block, and carrying out tempering on the molten slag heat in a step S7;

s7: electrifying, heating and tempering the slag generated in the step S6 in a tempering electric furnace, adding siliceous or alumino-silicate hazardous waste to adjust the silicate degree of the slag to 1.3-1.5, continuously volatilizing residual lead and zinc in the slag and discharging the residual lead and zinc into flue gas, converging the flue gas with the flue gas of a melting electric furnace, performing gravity dust removal and cloth bag dust removal to generate secondary ash containing zinc and lead, and returning the secondary ash containing zinc and lead to the step S1 as a zinc-containing raw material;

s8: the qualified quenched and tempered slag in the step S7 is sent to a slag cotton production system to produce a slag cotton plate, and after the slag self-flowing is finished, the residual iron-containing slag at the bottom of the slag ladle is left in a plurality of furnaces and then is poured back to the melting electric furnace in a thermal state to continue melting reduction;

preferably, in the step S1, the zinc-containing hazardous waste is pretreated and stored according to the type of the hazardous waste, and the waste catalyst is pretreated and stored according to the type of the carrier. The material granularity should accord with the pressure ball requirement, and the cubic material need be broken to below 1mm just can the compounding pressure ball, so, material and bentonite contact area are big, and the pelletizing intensity is high.

Preferably, the bentonite in the step S2 accounts for 1% -2% of the total mass of the rest materials, and the total mass of the rest materials refers to the total mass of the dry weight of 3 material components containing heavy metal hazardous waste, coke powder, quartz sand or lime.

Preferably, the screening in the step S4 is performed by a screening machine, and simultaneously, the undersize is crushed and returned to the step S2 for mixing.

Preferably, the maximum operating temperature of the reduction zone of the rotary kiln in said step S5 is not higher than 1100 ℃. The highest temperature of the existing Wilz process is generally up to over 1200 ℃, and the melting point of a slag system is 1300-1500 ℃. Reducing the temperature of the rotary kiln is a process path for avoiding ring formation. The invention controls the highest temperature of the reduction section not to be higher than 1100 ℃, namely lower than the melting temperature of the furnace charge by at least more than 200 ℃.

Preferably, a spare heat-preservation temporary storage device is arranged in the process of discharging the kiln slag into the melting and separating electric furnace in the step S6, so that the kiln slag can be preserved heat and the production rhythm can be adjusted when the melting and separating electric furnace is unsmooth in smelting or has a fault. According to the difference of the reducibility of metal oxides in the kiln slag, the residual Zn and Pb in the kiln slag are secondarily reduced and strongly volatilized into flue gas by adjusting the alkalinity, the temperature and the reducing atmosphere of the furnace slag of the melting electric furnace, the oxides of iron, nickel, chromium and manganese are reduced into metal simple substances and are gathered into molten iron, and the oxides of silicon, aluminum, calcium and magnesium are controlled not to be reduced and are completely led into the furnace slag. The temperature of the melting and separating electric furnace can be raised to 1600 +/-100 ℃, molten iron and molten slag can be well melted and separated, the produced molten iron is cast into pig iron blocks through an ingot mould, and the molten slag is discharged into a slag ladle and is conveyed to a tempering electric furnace for further tempering.

Preferably, in the step S7, a quenching and tempering electric furnace is used for quenching and tempering and temperature regulation of the slag; the hardening and tempering electric furnace adopts a double-electrode slag ladle direct-current electric furnace workstation, and the furnace cover adopts a water-cooled type liftable furnace cover. The slag ladle is placed on a movable rail trolley so as to conveniently enter a station for smelting and exit from the station for lifting. When the electric melting furnace is used for deslagging, the slag ladle is a slag container; after being filled, the slag ladle is hoisted to a rail trolley, the rail trolley drives into a smelting work station for smelting, and the slag ladle is a smelting container; after the tempering is finished, the slag ladle trolley is driven out of the workstation, the slag ladle is hoisted to the slag wool production line, and the slag ladle is a slag container of the slag wool production system.

Preferably, the slag wool production system in the step S8 is used for producing slag wool boards by a slag wool production line adopting a four-roller centrifugal-pendulum felting method, which is a mature process currently in the market.

In the embodiment of the application, the new process adopts various process combinations, makes good use of advantages and avoids disadvantages, can effectively treat various hazardous wastes containing heavy metals, and recovers various valuable metals. The single Wilz process has low kiln temperature, can only treat volatile metals such as zinc, lead and the like, and the produced kiln slag cannot be utilized. The single electric furnace process has controllable furnace temperature, can reduce iron, chromium, manganese, vanadium and other metals which are difficult to reduce, but can not produce zinc-containing materials into high-grade zinc oxide products. The combination of the Wilz process and the electric furnace process can achieve 1+1>2. Firstly, the waste catalyst is added into the zinc-containing material for treatment, so that the contradiction that the waste catalyst is small in amount and difficult to treat on a large scale is solved; the treatment capacity of the Wilz kiln is large, and the incorporation of the waste catalyst does not cause fundamental influence on the Wilz process. The Wilz kiln slag contains a large amount of FeO and SiO₂And CaO solves the problem that a large amount of iron ore, quartz stone or lime is required to be added for slagging in the smelting of the waste catalyst. The time of the materials in the Wilz kiln is long, the active carbon carrier of the waste catalyst is combusted for decarburization and can be used as a heat source or a reducing agent, while the silicon-based and aluminum-based carriers which are difficult to treat by the conventional method can fully carry out slagging reaction with basic oxides such as FeO, CaO, MgO and the like, and target metals which are difficult to reduce are fully pre-reduced, after the materials enter an electric furnace smelting link, the heating and smelting time of the melting electric furnace can be greatly reduced, so that not only is the electric charge saved, but also the capacity of the melting electric furnace can be reduced, and the investment is saved. Secondly, the process avoids the recovery burden of heavy metal zinc from being added to the Wilz process, but adopts the process of taking rotary kiln dezincification as a main process and taking melting electric furnace dezincification as an auxiliary process, the melting electric furnace has high temperature and strong reducing atmosphere, and the removing rate of residual zinc and lead which are difficult to volatilize in the rotary kiln is higher; the kiln slag has high iron content and low manganese, nickel, chromium and the like content, and iron becomes a trapping agent of the metals such as nickel, chromium, manganese and the like after being reduced into molten iron, so that the recovery rate of valuable metals is high, and the problems that a high-temperature smelting furnace is additionally added for smelting the waste catalyst and an iron-containing trapping agent is added are solved. Thirdly, the zinc-containing hazardous waste and the waste catalyst are completely converted into the products of secondary zinc oxide, alloy iron blocks and slag cotton plates through the combination of a Wilz kiln, a melting electric furnace, a tempering electric furnace and a slag cotton production line, so that the recycling and reduction of the heavy metal-containing hazardous waste are thoroughly realized. Fourthly, the ring formation is a special fault problem of the rotary kiln, the contradiction between the kiln temperature and the recovery rate of zinc and the ring formation cannot be overcome by adopting a single Wilz process, the kiln temperature is reduced by adopting a combination mode of adding bentonite into raw materials for pelletizing and screening, and the rotary kiln and a melting electric furnace are subjected to two-stage dezincification, so that the recovery rate of zinc is greatly improved, and the ring formation of the rotary kiln is thoroughly avoided. The invention has the following application contents: the pelletizing and screening process is added, namely, bentonite is added as a binder to increase the high-temperature strength of the pellets, and powder is completely screened before the pellets are fed into a kiln, so that ring formation is avoided. The kiln temperature is reduced, and ring formation is thoroughly avoided. Adding a treatment process of kiln slag, namely adding a melting electric furnace to reduce Zn, Pb, Fe, Ni, Cr and Mn and volatilize Zn and Pb to smokeAnd in the process, a tempering electric furnace is added to temper the slag, and a slag wool production process is added to produce the slag into the slag wool. Therefore, the recovery rate of the heavy metals in the zinc-containing hazardous waste and the waste catalyst is obviously improved, the iron-containing tailings generated in the original Wilz process and silicon-based and aluminum-based carriers with high melting points in the waste catalyst are completely eaten, dried and squeezed, waste materials are changed into valuable materials, the ring formation of a rotary kiln is thoroughly avoided, the production period is prolonged, and the production cost is reduced. The powder is the material basis for the formation of the loop. The local over-high temperature is the process condition for forming the ring. Therefore, the invention can improve the strength of the ball and avoid powder materials by adding the binder and pressing the ball and screening out the powder after drying. Secondly, the highest temperature in the kiln is controlled to be 200 ℃ below the melting temperature of furnace materials, so that ring formation can be thoroughly avoided. The method solves the technical problems of environmental pollution and resource waste caused by incapability of better utilizing zinc-containing hazardous waste and waste catalysts. The method has the advantages of high recovery rate of heavy metals, thorough avoidance of ring formation of the rotary kiln, good reduction effect of the iron-containing furnace slag, waste recycling, energy conservation and emission reduction.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, serve to provide a further understanding of the application and to enable other features, objects, and advantages of the application to be more apparent. The drawings and their description illustrate the embodiments of the invention and do not limit it. In the drawings:

FIG. 1 is a flow chart of a new process for comprehensive utilization of hazardous waste resources containing zinc according to the application;

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

As shown in fig. 1, the application relates to a new process for comprehensively utilizing zinc-containing hazardous waste resources, which comprises the following steps:

s1: zinc leaching residue, blast furnace cloth bag ash, zinc-containing electroplating sludge, etc., and waste zinc acetate activated carbon-based catalyst (fine powder, main component is C)>80% of Zn, about 10% of Zn), FCC spent catalyst (fine powder, main component of which is SiO)₂、Al₂O₃NiO) classification pretreatment and classification storage.

S2: continuously adding the hazardous waste containing the heavy metals, the coke powder, the bentonite, the quartz sand or the lime as material components into a mixer (a double-shaft mixer) according to a pre-calculated proportion, simultaneously controlling the water adding amount, and mixing to obtain a mixture, wherein the water content is controlled to be about 10%;

s3: the obtained mixture is pressed into pellets with the diameter of 15mm by a ball press machine and the pellets are dried, and the heat source can be the waste heat of the flue gas generated in a process line, such as the hot flue gas of a tempering electric furnace. When the moisture content of the pellets is less than 3%, the step S4 is carried out; the bentonite is used as a common binder in metallurgical production, and can increase the high-temperature strength of the pellets, so that the pellets are not easy to break to generate powder when rolling and extruding in a rotary kiln;

s4: screening the pellets by using a 5mm single-layer bar screen, feeding the screened pellets into the rotary kiln in the step S5, crushing the crushed pellets and powder under the screen by using a roller crusher, and conveying the crushed pellets and powder by using a belt to return to the mixer in the step S2 for re-mixing; the powder is a material basis of the ring formation of the rotary kiln, and the powder is completely avoided;

s5: reacting the screened pellets in a rotary kiln, reducing the highest temperature of a reduction zone in the kiln by controlling blast volume and other measures, and discharging flue gas containing zinc oxide and lead oxide after sequentially passing through a gravity settling system, a flue gas quenching system, a cloth bag filtering system and a tail gas treatment system, wherein low-grade zinc oxide obtained by the gravity settling is returned to the step S1 as a zinc-containing raw material because the zinc content does not meet the product requirement, and zinc hypoxide collected by the cloth bag filtering belongs to a product; discharging the red hot kiln slag from the kiln head, and performing treatment in step S6;

s6: and (3) directly discharging the kiln slag generated in the step (S5) to a melting electric furnace through a chute, adding quartz sand or lime to adjust the alkalinity of the furnace slag to 1.2-1.5, adding coke powder to ensure that the content of C is not higher than 8%, electrifying to raise the temperature to regulate and control the furnace temperature, performing secondary reduction volatilization on heavy metals such as zinc, lead and the like remaining in the kiln slag, discharging the heavy metals into flue gas, reducing oxides of iron, nickel, chromium and manganese in the kiln slag to a simple substance to produce molten iron, casting the molten iron after separating the iron slag into iron alloy blocks through an ingot mold, and thermally conveying the molten slag to the step (S7) for tempering.

S7: electrifying and heating the slag generated in the step S6 in a tempering electric furnace, adding silicon solid waste such as waste glass or silicon-aluminum solid waste such as waste silicon-aluminum bricks to adjust the silicate degree of the slag to 1.3-1.5, continuously volatilizing residual lead and zinc in the slag and discharging the residual lead and zinc into flue gas, converging the flue gas and the flue gas of a melting electric furnace, and performing gravity dust removal and cloth bag dust removal to generate zinc-containing secondary soot serving as a zinc-containing raw material to return to the step S1 for batching;

s8: the qualified quenched and tempered slag is hoisted to a slag wool production system along with a slag ladle in the step S7, a movable chute is connected to a slag hole, the slag automatically flows to the slag wool production system to produce a slag wool board, and the residual iron-containing slag in the slag ladle is poured back to the melting electric furnace in a thermal state after a plurality of slag are left in the slag ladle for continuous melting reduction;

wherein:

the zinc-containing hazardous waste and waste catalysts in the step S1 are subjected to classified pretreatment and classified storage, the blocky materials need to be crushed into powder of 1mm or less, and the powder and sludge can directly enter the step 2 through an automatic weighing and batching system;

the bentonite in the step S2 accounts for 1-2% of the total mass of the material. The total mass of the materials refers to the total mass of the dry weight of 3 material components containing heavy metal hazardous waste, coke powder, quartz sand or lime.

The pellets in step S3 are uniform in size and have significantly better motion characteristics than the fines in the rotary kiln. The pellets are heated uniformly in the kiln, the retention time is uniform, and the reduction volatilization reaction of the heavy metals Zn and Pb is more uniform.

And step S4, screening by using a bar screening machine. And (4) screening out the crushed balls and the powder with the size smaller than 5mm by using the screening machine, crushing the crushed balls and the powder by using the extrusion roller below the screen, and returning the crushed balls and the powder to the step S2 by using a material returning belt for re-mixing.

After the pellets are put into the kiln in the step S5, the temperature of the flue gas at the tail of the kiln is as high as above 700 ℃, the zinc acetate in the waste zinc acetate activated carbon-based catalyst is decomposed into zinc oxide, and the activated carbon starts to burn for decarburization. As the pellets move to the high temperature zone, NiO in the spent FCC catalyst begins to be reduced, and SiO with a high melting point₂、Al₂O₃The carrier begins to perform primary slagging reaction with basic oxides such as CaO in the materials; the reduction reaction of zinc oxide begins to occur gradually and becomes more and more intense; the metal oxides such as iron, chromium, manganese and the like which are difficult to reduce in the raw materials are pre-reduced into low-price metal oxides. The highest operation temperature of the reduction zone of the rotary kiln is controlled to be not higher than 1100 ℃ by measures such as controlling the blast volume of the kiln head, and the like, while the temperature of the existing Wilz process is generally higher than 1200 ℃, and the melting point of a slag system is 1300-1500 ℃. The invention controls the highest temperature of the reduction section not to be higher than 1100 ℃, namely lower than the melting temperature of the furnace charge by at least more than 200 ℃. After bentonite is added for pelletizing and powder is screened out, the temperature of the rotary kiln is reduced to thoroughly avoid ring formation.

And continuously discharging the kiln slag in the step S6 into a melting electric furnace for uninterrupted smelting. According to the difference of the reducibility of metal oxides in the furnace slag, the secondary reduction volatilization of Zn and Pb into flue gas is controlled by adjusting the temperature, the alkalinity of the furnace slag and the strength of the reducing atmosphere in the melting electric furnace, oxides of iron, nickel, chromium and manganese which are reduced in advance in the step S5 are reduced into simple substance metals, the oxides of silicon, aluminum, magnesium and calcium are controlled not to be reduced to form the furnace slag completely, the metal and the molten slag are gathered in a furnace hearth, and the slag and the iron are separated in the furnace hearth due to the difference of specific gravity of the metal and the molten slag. The melting electric furnace can be heated to 1600 +/-100 ℃ or even higher, so that the melt can be overheated, molten iron and molten slag can be well melted, the molten iron is cast through the ingot mould through the iron outlet to produce alloy iron blocks, and the hot melting slag automatically flows into a slag ladle through the slag outlet. The process is provided with a heat-preservation slag pot, when the melting electric furnace is unsmooth in smelting or breaks down to repair the furnace, the kiln slag is discharged into the heat-preservation slag pot to preserve heat and temporarily store the kiln slag, and meanwhile, the production rhythm is adjusted.

Quenching and tempering the slag by adopting a quenching and tempering electric furnace in the step S7; the hardening and tempering electric furnace adopts a double-electrode slag ladle direct-current electric furnace workstation, and the furnace cover adopts a water-cooled type liftable furnace cover. The furnace cover is provided with 4 holes, wherein 2 electrode holes, 1 feeding hole and 1 air extraction hole. After the slag ladle reaches a smelting station, putting down a water-cooled furnace cover and a double electrode, adding a tempering agent such as waste glass and the like from a feeding hole on the furnace cover, starting electrifying for tempering, and discharging flue gas into a dust removal system through an exhaust hole; after the hardening and tempering are finished, the furnace cover and the electrode are lifted, the slag ladle trolley is moved out of the workstation, and then the slag ladle is hoisted to a mineral wool production line.

The slag wool production system in the step S8 is a slag wool production line adopting a four-roller centrifugation-pendulum felt paving method. And a slag tap of the slag ladle is connected with a movable chute, and the slag automatically flows to a slag wool production line to produce a slag wool board. The process is the mainstream mature process in the current market and is not repeated.

The present embodiment has at least the following advantages:

(1) the new process adopts various process combinations, makes good use of advantages and avoids disadvantages, can effectively treat various hazardous wastes containing heavy metals, particularly waste catalysts which are difficult to treat by a smelting method, and recovers various valuable metals. The waste catalyst is added into the zinc-containing hazardous waste for treatment, so that the problem that the waste catalyst is small in amount and difficult to treat in a large scale is solved; the treatment capacity of the Wilz kiln is large, and the incorporation of the waste catalyst does not cause fundamental influence on the Wilz process. The Wilz kiln slag contains a large amount of FeO and SiO₂CaO solves the problem that a large amount of iron ore, quartz stone or lime needs to be additionally added for slagging in the smelting of the waste catalyst; reducing Fe in the kiln slag into molten iron in a melting electric furnace, wherein the molten iron is a trapping agent for metals such as Ni, Cr and the like in the smelting of the waste catalyst. The time of the materials in the Wilz kiln is long, the active carbon carrier of the waste catalyst is fully combusted for decarburization, the high-melting-point silicon-based, aluminum-based or silicon-aluminum-based carrier can fully carry out primary slagging reaction with FeO, CaO, MgO and other alkaline oxides, the target metal difficult to reduce is fully pre-reduced, and the temperature-rising smelting time of the melting electric furnace can be greatly reduced after the materials enter the electric furnace smelting linkNot only saves the electricity charge, but also reduces the capacity of the melting electric furnace and saves the investment.

(2) The recovery rate of valuable metals is high, and the harmless effect of hazardous wastes is obvious. The single Wilz process can only treat low-melting-point volatile metals such as zinc, lead and the like, and the produced kiln slag cannot be utilized. The single electric furnace process has controllable furnace temperature, can reduce iron, chromium, manganese and other metals which are difficult to reduce, but can not produce zinc-containing materials into high-grade zinc oxide products. The combination of the Wilz process and the electric furnace process can achieve the effect of 1+1> 2. The zinc and lead recovery rate can be greatly improved by adopting a two-stage dezincification process with the rotary kiln dezincification as a main process and the melting electric furnace dezincification as an auxiliary process; the melting electric furnace has high temperature, valuable metals such as Fe, Cr, Mn, Ni and the like which are difficult to reduce can be reduced into alloy iron to the maximum extent, and residual iron in the slag can be poured back to the melting electric furnace in a thermal state for continuous melting reduction after a plurality of slag retaining operations in the melting electric furnace and a slag wool production line.

(3) Through the combination of a Wilz kiln, a melting electric furnace, a tempering electric furnace and a slag cotton production line, zinc-containing hazardous waste and a waste catalyst are completely converted into products of zinc hypoxide, alloy iron and a slag cotton plate, so that the recycling and reduction of heavy metal hazardous waste are thoroughly realized. Most of the waste catalysts are aluminum-based, silicon-based or silicon-aluminum-based carriers, and the residual carriers after target metals are extracted are difficult to treat by adopting wet treatment. By adopting the process, the refractory aluminum-based, silicon-based or silicon-aluminum-based carrier is mineralized into slag to become the effective component of the slag wool.

(4) The ring formation of the rotary kiln is thoroughly avoided. The powder is the material basis for the formation of the loop. The local over-high temperature is the process condition for forming the ring. Therefore, the invention can improve the high-temperature strength of the balls and avoid powder materials by adding the binder to press the balls and screening out the powder after drying. Secondly, the highest temperature in the kiln is controlled to be more than 200 ℃ lower than the melting temperature of furnace burden, so that ring formation can be thoroughly avoided.

(5) Energy conservation and emission reduction. Multiple processes are combined, all the processes are connected in order, hot charging and hot conveying are carried out, and energy consumption is greatly reduced. The ring formation of the Waelz kiln is thoroughly avoided, the production period is greatly prolonged, the yield is increased, and the unit energy consumption of zinc-containing hazardous waste treatment is reduced. The water quenching link is saved, and a large amount of water resources are saved.

The melting and separating electric furnace adopts a submerged arc direct current electric furnace, and the most obvious appearance characteristic is that a furnace top graphite electrode is one, a furnace bottom anode is arranged at the furnace bottom, and the furnace mainly utilizes the resistance of raw materials or slag to convert electric energy into heat energy when in work. The electrodes are immersed in the melt, which is the heat exchange medium that provides the energy required for melting and chemical reactions of the material. The tempering electric furnace adopts a double-electrode direct-current electric furnace workstation. Compared with the alternating current electric arc furnace, the direct current electric arc furnace has the advantages of reduced consumption of graphite electrodes, small impact-flicker on a power grid, prolonged service life of a furnace lining, simplified structure, stirring of a molten pool and the like, and also has outstanding environmental protection performance. Compared with an alternating current electric furnace, the noise is reduced by 10-15 dB. The electric furnace uses electricity as energy, can greatly reduce the discharge amount of carbon and atmospheric pollutants, and particularly has the discharge amount of dioxin which is obviously lower than that of the Wilz process.

The method solves the technical problems of environmental pollution and resource waste caused by incapability of better utilizing zinc-containing hazardous waste and waste catalysts. The method has the technical effects of high recovery rate of heavy metals, high utilization rate of iron-containing slag, waste recycling, energy conservation and emission reduction, and thorough prevention of ring formation of the rotary kiln.

Claims

1. A novel process for comprehensively utilizing hazardous waste resources containing heavy metals is characterized by comprising the following steps:

s1: carrying out pretreatment and classified storage on hazardous waste containing heavy metals according to components, crushing blocky materials into powder of 1mm or below, storing the powder and sludge in a classified manner, and then entering step S2, wherein the heavy metals comprise: zinc, lead, nickel, chromium and manganese elements;

s2: adding the hazardous waste containing the heavy metals, bentonite, coke powder, quartz sand or lime as material components into a mixer, and adding water for mixing to obtain a mixture;

s3: preparing the mixture obtained in the step S2 into pellets, drying the pellets, and entering the step S4 when the moisture content of the pellets is less than 3%;

s4: screening the pellets, feeding the screened pellets into the rotary kiln in the step S5, and returning the screened powder to the step S2 for mixing;

s5: reacting the screened pellets in a rotary kiln to reduce the operation temperature of a reduction zone in the rotary kiln, discharging flue gas generated by the rotary kiln after sequentially passing through gravity settling, flue gas quenching, cloth bag filtering and a tail gas treatment system, wherein primary flue dust containing zinc and lead obtained after the gravity settling is used as a raw material and is returned to the step S1, and collecting to obtain zinc hypoxide after the cloth bag filtering;

s6: discharging the kiln slag generated by the rotary kiln in the step S5 to a melting and separating electric furnace for smelting, adjusting the furnace temperature, the carbon content and the slag alkalinity in the electrifying smelting process, reducing iron, nickel, chromium and manganese in the materials to generate molten iron, secondarily reducing and volatilizing residual zinc and lead and discharging the residual zinc and lead into flue gas, feeding all other substances generated by the melting and separating electric furnace into molten slag, carrying out ingot casting on the molten iron after slag and iron separation to generate alloy iron blocks, and discharging the molten slag to a slag ladle for heating and sending the slag to the tempering electric furnace in the step S7 for tempering;

s7: starting the slag generated in the step S6 in a tempering electric furnace, raising the temperature, adding solid waste silicon or silicon-aluminum for adjusting the silicate degree of the slag in the tempering electric furnace to 1.3-1.5, continuously volatilizing residual zinc and lead in the slag and discharging the residual zinc and lead into flue gas, and returning the flue gas generated by the tempering electric furnace and the melting electric furnace to the step S1 as a raw material after the flue gas is subjected to gravity dust removal and cloth bag dust removal to generate secondary ash containing zinc and lead;

s8: and (5) delivering the qualified quenched and tempered slag in the quenching and tempering electric furnace in the step (S7) to a slag wool production system to produce a slag wool board.

2. The new process for comprehensively utilizing resources containing heavy metal dangerous wastes according to claim 1, wherein the heavy metal dangerous wastes in the step S1 comprise waste catalysts and zinc-containing dangerous wastes, the zinc-containing dangerous wastes are classified and pretreated and stored according to the types of the dangerous wastes, and the waste catalysts are classified and pretreated and stored according to the types of carriers.

3. The new process for comprehensively utilizing the heavy metal-containing hazardous waste resources as claimed in claim 1, wherein in the step S2, the percentage of bentonite in the total mass of the rest materials is 1% -2%.

4. The new process for comprehensively utilizing the waste resources containing the heavy metals in danger according to claim 1, characterized in that the screening in the step S4 is performed by a screening machine, and simultaneously, the undersize is crushed to form powder.

5. The new process for comprehensively utilizing the hazardous waste resources containing the heavy metals according to claim 1, wherein the operation temperature of the reduction zone in the rotary kiln is reduced to not higher than 1100 ℃ in the step S5.

6. The new process for comprehensively utilizing the hazardous waste resources containing the heavy metals according to claim 1, wherein the kiln slag in the step S6 is directly discharged into an electric melting and separating furnace and is provided with a standby heat preservation temporary storage device.

7. The new process for comprehensively utilizing resources at risk of waste containing heavy metals according to claim 1, wherein the electric quenching and tempering furnace in the step S7 is a double-electrode slag-coated direct current electric furnace workstation, and the furnace cover of the electric quenching and tempering furnace is a water-cooled type liftable furnace cover.

8. The new process for comprehensively utilizing the hazardous waste resources containing the heavy metals according to claim 1, wherein the slag wool production system in the step S8 adopts a four-roller centrifugation-pendulum felting process slag wool production line.

9. The new process for comprehensively utilizing the heavy metal-containing hazardous waste resources as claimed in claim 1, wherein the melting and separating electric furnace is a furnace bottom anode direct current submerged arc electric furnace.