CN112048625A - Lead-zinc oxide ore recycling harmless treatment system and method - Google Patents
Lead-zinc oxide ore recycling harmless treatment system and method Download PDFInfo
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- CN112048625A CN112048625A CN202010686592.2A CN202010686592A CN112048625A CN 112048625 A CN112048625 A CN 112048625A CN 202010686592 A CN202010686592 A CN 202010686592A CN 112048625 A CN112048625 A CN 112048625A
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Abstract
The invention relates to a lead-zinc oxide ore recycling harmless treatment system and method, belonging to the technical field of lead-zinc oxide ore treatment. Zinc oxide smoke dust produced by the reduction and volatilization of the rotary kiln is recovered after enrichment; the slag produced by the rotary kiln is cooled by a cooler to produce secondary hot air and low-temperature harmless slag, the secondary hot air is sent to a predecomposition furnace, the material is dried and a waste heat boiler is recycled, and the harmless slag can be used for producing building materials; the invention fully recycles the waste heat of the flue gas and the slag, fully utilizes the advantage of large specific surface area of the powder, improves the heat exchange and reduction volatilization rates, greatly improves the treatment capacity and the heat energy utilization rate of the lead-zinc oxide ore and reduces the production cost.
Description
Technical Field
The invention belongs to the technical field of lead-zinc oxide ore treatment, and particularly relates to a low-grade lead-zinc oxide ore recycling harmless treatment system and method.
Background
The lead-zinc oxide ore has a complex structure and high ore dressing difficulty, and particularly the ore dressing difficulty of low-grade lead-zinc oxide ore is obvious. Meanwhile, with the continuous development and utilization of high-quality lead and zinc resources, the efficient development and utilization of low-grade lead-zinc oxide ores becomes increasingly important; when high-quality lead and zinc resources are exploited, a large amount of low-grade lead-zinc oxide ores cannot be utilized due to high grade and recovery processing cost, so that not only is the resources wasted, but also the ecological environment of a mining area is seriously damaged. How to economically and efficiently utilize low-grade lead-zinc oxide ore is a major problem in the lead-zinc industry.
At present, the method for resource utilization of lead-zinc oxide ore mainly comprises a mineral separation process, a dressing and smelting combined process and a high-temperature reduction volatilization process. The beneficiation process mainly adopts a flotation agent to enrich sulfide ores, and has more researches by scholars at home and abroad aiming at the beneficiation process of the sulfide ores, so that details are not repeated, and the beneficiation process has the problems of higher beneficiation difficulty, more complex treatment process, higher cost and low yield particularly for the flotation of low-grade ores. The combined process of dressing and smelting is to leach the oxidized ore in acid first to recover the oxidized ore, and then to perform flotation and ore dressing to recover the sulfide ore, the leachate produced in the acid leaching process has low zinc content, high acid consumption and large wastewater amount, and simultaneously produces a large amount of leaching slag which belongs to hazardous waste, and the leaching slag needs to be further treated in a harmless way, so that the waste acid and the waste slag are difficult to treat, the treatment cost is high, the environment is protected and the environment is difficult to reach the standard, and the economy is difficult to accept. The high-temperature reduction volatilization process refers to that lead-zinc oxide ore is subjected to high-temperature reduction volatilization in a high-temperature fire smelting device such as a fuming furnace, a rotary kiln, a tunnel kiln and the like to generate zinc oxide smoke dust and furnace slag, and the produced furnace slag is general solid waste. At present, when lead and zinc ores are treated, a rotary kiln high-temperature reduction volatilization process belongs to a mainstream process and has great advantages, but the process has the disadvantages of low heat energy utilization rate (about 10 percent of heat utilization rate), high energy consumption, low productivity and high production cost. For this reason, a great deal of effort is also being expended by technical workers and developers to reduce the energy consumption of the high-temperature reduction process. For example, in patent CN111270085A, a vacuum extractor is provided to reduce and volatilize the rotary kiln in a vacuum state, and the partial pressure of zinc vapor in the system is reduced by negative pressure, so as to reduce the temperature required for reduction and volatilization, thereby saving energy. Patent CN106766870A improves heat utilization by adding a heat exchanger outside the reduction zone of the rotary kiln. The methods have certain help in improving the heat energy utilization rate of the rotary kiln, but have limited effects, the heat energy can not be fully utilized, and the problem of high energy consumption of the high-temperature reduction volatilization process is still not solved. The existing smelting equipment has high energy consumption and high production cost, cannot be accepted by enterprises more and more, and has a plurality of problems of high energy consumption and high cost, which become main problems for restricting the recycling and harmless treatment of low-grade lead zinc oxide.
Disclosure of Invention
Taking the prior lead-zinc oxide ore high-temperature reduction volatilization equipment with the treatment capacity of 600t/d as an example, zinc oxide smoke dust is produced by reduction volatilization at 1300 ℃ under strong reducing atmosphere. The mass ratio of the coal to the ore is about 50%, and the problems of small treatment capacity, high production cost and the like exist. Aiming at the problems, through a large amount of test work and creative research, the inventor sets a preheating unit and a predecomposition furnace by optimizing and transforming high-temperature reduction volatilization equipment, fully utilizes reduction volatilization heat energy, fully utilizes waste heat of flue gas and slag, effectively prolongs contact time of materials and flue gas, and greatly improves heat utilization rate and material reduction volatilization speed after preheating and predecomposition reaction of the materials through granularity control of ores. By adopting the technical scheme of the invention, the heat energy utilization rate is up to 45-65%, and the fuel consumption is 40% of that of the prior art. Meanwhile, because the reduction volatilization rate is accelerated, the treatment capacity of the oxidized ore can reach 400t/h, which is more than 15 times of the treatment capacity of the existing production process.
Therefore, the invention mainly has two aims, the first aim is to provide a lead-zinc oxide ore recycling harmless treatment system, and the second aim is to provide a lead-zinc oxide ore recycling harmless treatment method.
The first purpose of the invention is realized by the following technical scheme:
the lead-zinc oxide ore recycling harmless treatment system and method comprise a preheating unit 1, a predecomposition furnace 2, a rotary kiln 3 and a cooler 4, wherein lead-zinc oxide ore is added from the preheating unit 1; the preheating unit 1 is provided with a discharge port communicated to the pre-decomposition furnace 2; the top flue gas outlet of the pre-decomposition furnace 2 is communicated to the preheating unit 1, the pre-decomposition furnace 2 is provided with a pulverized coal feeding hole, a granular coal feeding hole and a secondary air port, and the bottom of the pre-decomposition furnace 2 is communicated with the rotary kiln 3.
Further, the lead-zinc oxide ore recycling harmless treatment system also comprises a cooler 4; one end of the cooler 4 is connected with the kiln head of the rotary kiln 3, and the other end is provided with a cold slag discharge hole; secondary hot air generated by the cooler 4 is communicated to the pre-decomposition furnace 2 through a pipeline; and a hot air spray gun is arranged at the kiln head of the rotary kiln 3 to provide combustion air.
Further, the preheating unit 1 is formed by connecting preheaters through pipelines; and the lead and zinc oxide material is added from a feed inlet of the preheating unit.
Further, the preheating unit 1 can be set to preheat the material by directly contacting with the flue gas, and also can be set to preheat the material by indirectly contacting with the flue gas.
Furthermore, the lead-zinc oxide ore can be fed continuously or intermittently.
Further, the temperature of the flue gas at the outlet of the preheating unit is less than or equal to 400 ℃.
The second purpose of the invention is realized by the following technical scheme:
the method for recycling the lead-zinc oxide ores into harmless resources comprises the following steps:
A. crushing, drying, grinding and homogenizing lead-zinc oxide ores;
B. adding lead-zinc oxide ore into a preheating unit for preheating;
C. under an oxidizing atmosphere, adding preheated lead and zinc oxide into a predecomposition furnace to complete predecomposition reaction and remove impurities such as sulfur, chlorine and the like; b, sending high-temperature flue gas generated by the pre-decomposition reaction to a preheating unit in the step B to preheat lead-zinc oxide ore;
D. the intermediate material produced by the pre-decomposition furnace enters a rotary kiln, and reduction and volatilization of lead and zinc in lead-zinc oxide ores are completed in a reducing atmosphere;
E. and (4) recovering the waste heat of the high-temperature slag generated by the reduction reaction for pre-decomposition in the step C and wind for combustion in the step D.
In one step, the high-temperature preheating in the step B means that in the preheating unit, the high-temperature flue gas directly exchanges heat with the lead-zinc oxide ore or the high-temperature flue gas indirectly preheats the lead-zinc oxide ore.
Further, the pre-decomposition temperature is not less than 900 ℃ under the oxidizing atmosphere in the step C.
Further, under the reducing atmosphere in the step D, the reaction temperature is more than or equal to 1100 ℃.
Further, the lead-zinc oxide ore in the step A is one ore or more than two ore mixtures of lead-zinc oxide ore, low-grade lead-zinc oxide ore or oxygen-sulfur mixed ore
The invention has the beneficial effects that:
according to the invention, the preheating unit is arranged, the lead-zinc oxide ore is preheated by the preheating unit, the lead-zinc oxide ore is preheated in the preheating unit, and the temperature of the lead-zinc oxide ore at the outlet of the preheating unit is more than or equal to 600 ℃. The smelting flue gas and the lead-zinc oxide ore exchange heat in the preheating unit, so that the waste heat in the flue gas can be effectively recovered, the temperature and the reaction rate of the lead-zinc oxide ore entering the furnace can be increased, and the aims of improving the production capacity of a lead-zinc oxide ore treatment system and reducing the energy consumption are fulfilled.
The invention arranges the pre-decomposition furnace and controls the pre-decomposition furnace to be oxidizing atmosphere, the powdered coal is completely burnt in the pre-decomposition furnace, the temperature of the lead-zinc oxide ore is further raised, carbonates such as CaCO3 and the like are heated and decomposed, and sulfur in sulfides such as ZnS and the like is oxidized and removed. Combustible materials such as CO and the like which are not completely combusted in the rotary kiln are completely combusted at the position, so that the utilization rate of fuel is effectively improved; meanwhile, hot air of the rotary kiln is recycled through the cooler and enters the predecomposition furnace, heat energy is effectively recycled, and impurities can be removed from the predecomposition furnace only by using less fuel.
The invention uses the cooler, not only ensures the carbon residue in the kiln slag to be completely combusted, but also can effectively recover the waste heat of the kiln slag, reduces the temperature of the kiln slag from 900-1100 ℃ to less than or equal to 120 ℃, produces high-temperature hot air to be used as secondary air of the rotary kiln and the pre-decomposition furnace, and the residual hot air can be used for waste heat power generation or ore grinding and drying materials. Due to the use of the cooler, the utilization rate of the waste heat in the kiln slag reaches more than 60 percent, the heat utilization rate of the system can be effectively improved, and the production cost is reduced.
The invention creatively uses the preheating unit, the predecomposition furnace, the cooling machine and other devices, thereby not only realizing the recovery and utilization of the waste heat of the flue gas and the kiln slag, but also strengthening the metallurgical reaction process and accelerating the reduction and volatilization of the materials in the furnace. Through the measures, the processing capacity and the heat utilization rate of the processing system are greatly improved compared with those of the traditional production process. The daily treatment capacity of the lead-zinc oxide ore can reach more than 15 times of that of the traditional production process; the heat utilization of the system can reach more than 50 percent, which is about 5 times of that of the rotary kiln or the fuming furnace through reduction and volatilization. Due to the great improvement of the heat utilization rate and the productivity, the lead-zinc oxide ore treatment cost is reduced to about 350 yuan/t, which is only 1/2 of the reduction and volatilization production cost of the existing rotary kiln or fuming furnace.
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FIG. 1 is a schematic diagram of the apparatus of the present invention;
FIG. 2 is a schematic diagram of the structure of embodiment 2 of the system of the present invention;
in the figure, 1-preheating unit, 2-predecomposition furnace, 3-rotary kiln and 4-cooler.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, preferred embodiments of the present invention will be described in detail below to facilitate understanding of the skilled person.
In the specific embodiment, the percentage content is the mass percentage content unless otherwise specified.
The invention provides a lead-zinc oxide ore recycling harmless treatment system.
Example 1:
a lead-zinc oxide ore recycling harmless treatment system, as shown in fig. 1, the treatment system comprises: preheating unit 1, predecomposition stove 2, rotary kiln 3 and cooler 4.
Preheating unit 1 and predecomposition stove 2 intercommunication, indirect or direct contact of zinc oxide flue gas that lead zinc oxide material and follow predecomposition stove 2 come out in preheating unit 1 accomplishes preheating of lead zinc oxide material, and preheating unit 1 can adopt any gas-solid indirect heat transfer equipment that can realize the direct or indirect contact heat transfer of zinc oxide smoke and dust and lead zinc oxide material, for example: the cyclone preheating unit, the multi-hearth furnace type preheating unit and the sleeve type heat exchange equipment with the inner layer as a material channel and the outer layer as a flue gas channel and the like. The preheating unit 1 can preheat lead and zinc oxide materials, and meanwhile, heat in flue gas is recycled, so that the heat utilization rate is improved. The temperature of the flue gas discharged from the preheating unit 1 is less than or equal to 400 ℃.
The kiln head of the rotary kiln 3 is provided with a hot air spray gun which provides combustion air or heat energy for the rotary kiln 3. The bottom of the pre-decomposition furnace 2 is communicated with the kiln tail of the rotary kiln 3. One end of a cooler 4 is connected with the kiln head of the rotary kiln 3, the other end of the cooler 4 is a cold slag discharge hole, and the cooler 4 recovers the waste heat in the rotary kiln 3 to generate hot air at the temperature of 600-900 ℃ and sends the hot air into the pre-decomposition furnace 2 and the rotary kiln 3 as secondary combustion air.
The cooler 4 is arranged to recover the waste heat of the high-temperature kiln slag generated by the rotary kiln 3 to obtain low-temperature furnace slag and hot air of 600-900 ℃, and the hot air is recovered and sent to the pre-decomposition furnace 2 or the rotary kiln 3 for recycling. By recycling the flue gas of the rotary kiln 3 and the kiln slag waste heat, the consumption of pulverized coal in the pre-decomposition furnace 2 can be greatly saved, the pulverized coal in the pre-decomposition furnace and CO which is not completely combusted in the rotary kiln can be completely combusted, and the temperature in the pre-decomposition furnace 2 is more than or equal to 900 ℃. In the pre-decomposition furnace 2, carbonate such as CaCO3 is completely decomposed, and sulfur in sulfide such as ZnS is removed by oxidation.
The pre-decomposition furnace 2 is provided with a pulverized coal feeding hole, a secondary air hole and a granulated coal feeding hole, and the granulated coal feeding hole liquid can be arranged at the kiln tail of the rotary kiln. Adding pulverized coal with granularity less than or equal to 80 μm and water content less than or equal to 1% from a pulverized coal feed inlet to supplement heat for the pre-decomposition furnace 2; the secondary tuyere is used for providing oxygen and has the functions of providing oxygen for pulverized coal combustion and oxidative desulfurization; the addition of the granulated coal with the granularity of 2mm or more and 8mm or less and the moisture of 10% or less into the granulated coal charging port, the addition of the granulated coal into the rotary kiln 3 through the pre-decomposition furnace 2 provides heat for the rotary kiln, and more importantly, provides reducing atmosphere to achieve the purpose of reducing and volatilizing ZnO and PbO.
The adding amount of the pulverized coal in the pre-decomposition furnace 2 is controlled to be 0-15% of the lead-zinc oxide ore amount, the excess air coefficient in the pre-decomposition furnace 2 is controlled to be 1.2-1.5, the pulverized coal is more fully combusted, the oxidizing atmosphere in the furnace is ensured, and the pulverized coal and CO which is not completely combusted in the rotary kiln are completely combusted in the pre-decomposition furnace 2. The predecomposition furnace 2 is arranged in a cylindrical shape, the furnace waist is contracted, and refractory bricks are lined. The waist contraction can accelerate the flow velocity of smoke gas at the waist, so that the flow velocity of the smoke gas and the mineral powder is changed suddenly, the dispersion effect is achieved, the lead zinc oxide mineral powder is more fully contacted with the pulverized coal and the smoke gas, the falling time of the lead zinc oxide mineral powder is prolonged, and the materials are ensured to be fully reacted in the furnace.
The addition of the granular coal of the pre-decomposition furnace 2 is controlled to be 6-15% of that of the lead-zinc oxide ore, the excess air coefficient of the rotary kiln 3 is controlled to be 0.8-1.2, the rotary kiln is ensured to be in a strong reducing atmosphere, the temperature in the kiln is more than or equal to 1100 ℃, and ZnO and PbO in the materials are completely volatilized to enter flue gas. The granular coal added from the pre-decomposition furnace 2 does not substantially participate in the reaction in the pre-decomposition furnace 2, and enters the rotary kiln to be combusted and provide reducing atmosphere so as to reduce and volatilize the lead-zinc oxide ore.
The temperature of the kiln slag produced by the rotary kiln is as high as 900-.
The lead-zinc oxide ore recycling harmless treatment system can adopt continuous feeding or intermittent feeding. Intermittent feeding is adopted, when the zinc content of the material in the pre-decomposition furnace 2 reaches 15-35%, the feeding is stopped, the zinc-containing material in the system is continuously reduced and volatilized to produce zinc oxide smoke, the zinc oxide smoke is recycled in a dust collection system, and the zinc content of the obtained smoke is 45-60%. After the zinc-containing smoke dust is recovered, continuously feeding materials, and circulating the steps. Continuous feeding is adopted, when the zinc-containing grade of the material in the pre-decomposition furnace 2 reaches 25-45%, a discharge port at the bottom of the pre-decomposition furnace is opened to discharge the zinc-containing material, and the zinc is recovered by fire treatment or wet treatment. The discharging can be performed in an intermittent manner or in a continuous manner, and materials with higher zinc content can be obtained through the intermittent discharging.
Example 2:
a lead-zinc oxide ore recycling harmless treatment system is characterized in that a preheating unit is a cyclone preheating unit, and the rest is the same as that in the embodiment 1. As shown in fig. 2, the processing system includes: cyclone preheating unit 1, predecomposition furnace 2, rotary kiln 3 and cooler 4. The cyclone preheating unit 1 is formed by connecting 5-grade cyclone dust collectors through pipelines (as shown in the attached figure 2, C1 represents a first-grade cyclone dust collector, C2 represents a second-grade cyclone dust collector, and the like). Lead-zinc oxide ore is added from a connecting pipeline between a 1 st-stage cyclone dust collector C1 and a 2 nd-stage cyclone dust collector C2 of the preheating unit, the lead-zinc oxide ore directly contacts with flue gas in the cyclone dust collectors and the pipeline for heat exchange, waste heat in the flue gas is recovered, and the lead-zinc oxide ore is preheated to 600-900 ℃. The 2 furnace tops exhansts of predecomposition stove communicate to preheating unit 5 th grade cyclone C5 air intakes, cyclone preheating unit 14 th grade cyclone C4 discharge opening communicates to the middle part of predecomposition stove 2, because whole cyclone separation system is the operation under the negative pressure, if communicate C4 discharge opening to the upper portion of predecomposition stove 2, then a large amount of lead-zinc oxide ore is not fully reacted at the predecomposition stove and is taken away promptly, set up at the middle part, then can guarantee the powdered ore fully reaction that gets down from C4 discharge opening. The 5 th stage cyclone dust collector C5 discharge port is communicated to the bottom of the pre-decomposition furnace 2. The kiln head of the rotary kiln 3 is provided with a hot air spray gun which provides combustion air or heat energy for the rotary kiln 3. The bottom of the pre-decomposition furnace 2 is communicated with the kiln tail of the rotary kiln 3. The cooler 4 adopts a grate cooler, one end of the cooler 4 is connected with the kiln head of the rotary kiln 3, the other end of the cooler 4 is a cold slag discharge hole, and the grate cooler 4 recovers the waste heat in the rotary kiln 3 to produce hot air with the temperature of 600-900 ℃ and sends the hot air into the pre-decomposition furnace 2 and the rotary kiln 3 as secondary combustion air.
The cyclone preheating unit 1 consists of 5-grade cyclone dust collectors, a C1 discharge opening of the 1 st-grade cyclone dust collector is communicated to a C3 outlet flue of the 3 rd-grade cyclone dust collector through a pipeline, and a C2 discharge opening of the 2 nd-grade cyclone dust collector is communicated to a C4 outlet flue of the 4 th-grade cyclone dust collector through a pipeline. By adopting the structure, the full contact between the materials and the flue gas can be ensured, the preheating time is prolonged, and the purpose of improving the heat utilization rate is achieved. The flue gas treated by the cyclone preheating unit 1 is discharged from an outlet of the 1 st-stage cyclone, and the temperature of the outlet flue gas is less than or equal to 400 ℃.
The invention also provides a recycling harmless treatment method for the lead-zinc oxide ores.
Example 1: (direct contact Heat exchange)
A recycling harmless treatment method for lead and zinc oxide comprises the following specific steps:
(1) the 100000t component is Pb 1.26%; zn 6.73%; 27.86 percent of CaO; SiO 22 22.34%； Al2O3 2.35 percent; 1.57 percent of MgO; and (3) sequentially crushing and ball-milling the low-grade lead-zinc oxide ore with 0.34 percent of S (the oxidation rate of lead and zinc reaches 75 percent). The granularity after crushing is less than or equal to 35mm and accounts for 80 percent; ball milling to obtain material with granularity not more than 80 micron and water content not more than 0.5%.
(2) 24000t of anthracite containing 65 percent of carbon, having the granularity of not less than 2mm and not more than 8mm and having the moisture of not more than 10 percent is divided into two parts, wherein 12000t of anthracite is subjected to ball milling, the granularity of powdered coal is not more than 80 mu m, and the moisture of the powdered coal is not more than 1 percent; in addition, 12000t of the prepared coal particles with the granularity of more than or equal to 2mm and less than or equal to 8mm and the moisture of less than or equal to 10 percent are piled up for standby.
(3) A production system with the processing capacity of 5000t/d is adopted, the ball-milled lead-zinc oxide ores are uniformly added into a preheating unit according to the material quantity of 250t/h, the temperature of flue gas at the outlet of the preheating unit is controlled to be 310 ℃, the outlet pressure is-5800 Pa, and the working condition air speed is 12 m/s. The lead-zinc oxide ore is preheated to 860 ℃.
(4) Uniformly spraying pulverized coal with the particle size of less than or equal to 80 mu m and the water content of less than or equal to 1% into a pre-decomposition furnace at the speed of 18.4t/h, controlling the air excess coefficient to be 1.25, and enabling the temperature in the furnace to be 1150 ℃ in an oxidizing atmosphere. Fully burning the pulverized coal in the pre-decomposition furnace and the residual CO produced in the rotary kiln; the lead-zinc oxide ore entering the pre-decomposition furnace from the preheater contains the impurities of sulfur, arsenic, fluorine, chlorine and the like which are removed, and CaCO3And decomposing the carbonate. And (4) dust-collecting the tail gas and then desulfurizing.
(5) Uniformly adding the granulated coal with carbon content of 65%, granularity of 2mm or more and less than 8mm and moisture of 10% or less into a predecomposition furnace at a speed of 15t/h, controlling the air excess coefficient of the rotary kiln to be 0.85, and controlling the temperature in the rotary kiln to be 1350 ℃ in the rotary kiln.
(6) After continuous feeding for 5 hours, enriching the zinc in the lead-zinc oxide ore in the preheater to 35%, opening a discharge opening at the bottom of the predecomposition furnace to discharge the high-zinc-content material, and carrying out pyrogenic or wet treatment to recover the zinc metal. The method can realize continuous feeding, batch type or continuous discharging.
(7) Delivering the 1240 ℃ kiln slag produced by the rotary kiln to a cooler for recovering waste heat, and producing the kiln slag with the temperature of 85 ℃ and hot air with the temperature of 950 ℃. The thermal efficiency of the cooler is more than or equal to 65 percent. The produced hot air is conveyed to the kiln head of the rotary kiln and the predecomposition furnace to be used as secondary combustion air, the residual hot air is used as a drying heat source for preparing coal powder and oxidizing the lead-zinc ore, and the rest of the hot air enters a waste heat boiler to generate power at a low temperature.
Example 2: (indirect contact Heat exchange)
A method for recycling lead-zinc oxide ore without harm comprises the following steps:
(1) 100 ten thousand t of Pb is 5.26 percent; 13.73 percent of Zn; 17.09% of CaO; SiO 22 35.94%； Al2O3 0.85 percent; 3.57 percent of MgO; and (3) crushing and ball-milling 5.34 percent (the oxidation rate of lead and zinc reaches 55 percent) of low-grade lead-zinc oxide ore. The granularity after crushing is less than or equal to 18mm and accounts for 75 percent; ball milling to obtain material with granularity not more than 75 micron and water content not more than 0.9%.
(2) Dividing 20 ten thousand tons of anthracite with 58 percent of carbon content, more than or equal to 2mm and less than or equal to 8mm of granularity and less than or equal to 10 percent of moisture into two parts, wherein 8 ten thousand tons of anthracite is ball-milled, the granularity of powdered coal is less than or equal to 80 mu m, and the moisture is less than or equal to 1 percent; in addition, 12 ten thousand tons of the granular coal are prepared, wherein the granularity is more than or equal to 2mm and less than or equal to 8mm, and the moisture is less than or equal to 10 percent and stacked for standby.
(3) And uniformly adding the ball-milled lead-zinc oxide ore into a preheater according to the material quantity of 500t/h by adopting a production system with the processing capacity of 10000t/d, and controlling the temperature of the smoke gas at the outlet of the preheater to 385 ℃, the outlet pressure to-7000 Pa and the working condition air speed to 12 m/s. The lead-zinc oxide ore is preheated to 715 ℃.
(4) Uniformly spraying pulverized coal with granularity less than or equal to 80 mu m and water content less than or equal to 1% into the pre-spraying device at a speed of 32.5t/hIn the decomposing furnace, the air excess coefficient is controlled to be 1.45, and the inside of the pre-decomposing furnace is in an oxidizing atmosphere at the temperature of 1080 ℃. Fully burning the pulverized coal in the pre-decomposition furnace and CO which is not burnt in the rotary kiln; the lead-zinc oxide ore entering the predecomposition furnace from the cyclone preheater contains the impurities of sulfur, arsenic, fluorine, chlorine and the like, and CaCO3And decomposing the carbonate. And (4) dust-collecting the tail gas and then desulfurizing.
(5) Uniformly adding the coal granules with carbon content of 58%, particle size of 2mm or more and 8mm or less and water content of 10% or less into a predecomposition furnace at a speed of 62.5t/h, controlling the air excess coefficient of the rotary kiln to be 0.95, enabling the rotary kiln to be in a strong reducing atmosphere, and enabling the temperature in the rotary kiln to be 1350 ℃.
(6) Zinc oxide smoke produced by reduction and volatilization of the rotary kiln enters an outer layer smoke pipeline of the preheating unit through a predecomposition furnace to be sent for dust collection treatment, zinc oxide smoke dust containing 55% of zinc is obtained after dust collection, and zinc oxide smoke dust is continuously produced by continuously feeding in the production process. The method has the advantages that the heat exchange effect of the preheating unit is poor compared with that of direct contact heat exchange, but the production process is continuous and stable. Is suitable for treating materials with zinc content of more than or equal to 10 percent.
(7) And (3) conveying the 1160 ℃ kiln slag produced by the rotary kiln to a cooling machine for recovering waste heat, and producing the kiln slag with the temperature of 115 ℃ and hot air with the temperature of 1040 ℃. The thermal efficiency of the cooler is more than or equal to 58 percent. The produced hot air is conveyed to the kiln head of the rotary kiln and the predecomposition furnace to be used as secondary combustion air, the residual hot air is used as a drying heat source for preparing coal powder and oxidizing the lead-zinc ore, and the rest of the hot air enters a waste heat boiler to generate power at a low temperature.
Example 3: (cyclone preheating unit preheating)
A method for recycling lead-zinc oxidized ore without harm comprises the following steps:
(1) the raw material of 50000t comprises Pb 2.26%, Zn 9.73%, CaO 21.86% and SiO2 28.34% Al2O3 The low-grade lead-zinc oxide ore with 0.35 percent of MgO, 0.57 percent of S and 4.34 percent of lead and zinc (the oxidation rate of lead and zinc reaches 60 percent) is crushed and ball-milled in sequence. The granularity after crushing is less than or equal to 25mm, and accounts for 70 percent; ball milling the material to obtain a product with a particle size of less than or equal to 60 μm and a water content of less than or equal to 0.8%.
(2) 10000t of anthracite with the carbon content of 60 percent, the granularity of 2mm or more and less than or equal to 6mm and the moisture of 8 percent is divided into two parts, wherein 5000t of anthracite is ball-milled, the granularity of powdered coal is less than or equal to 60 mu m, and the moisture of powdered coal is less than or equal to 0.6 percent; in addition, 5000t of the prepared coal particles are piled up for standby use, wherein the particle size of the coal particles is more than or equal to 2mm and less than or equal to 8mm, and the water content of the coal particles is less than or equal to 10%.
(3) And uniformly adding the ball-milled lead-zinc oxide ore into a cyclone preheater according to the material quantity of 136t/h by adopting a production system with the processing capacity of 3000t/d, and controlling the temperature of smoke gas at the outlet of the cyclone preheater to be 290 ℃, the outlet pressure to be 6000Pa and the working condition air speed to be 8 m/s. The lead-zinc oxide ore was preheated to 960 ℃.
(4) Uniformly spraying pulverized coal with the particle size of less than or equal to 60 mu m and the water content of less than or equal to 0.6 percent into the pre-decomposition furnace at the speed of 10.9t/h, controlling the air excess coefficient to be 1.15, and enabling the inside of the pre-decomposition furnace to be in an oxidizing atmosphere at the temperature of 1050 ℃. Fully burning the pulverized coal in the pre-decomposition furnace and CO which is not completely burned in the rotary kiln; the lead-zinc oxide ore entering the predecomposition furnace from the cyclone preheater contains the impurities of sulfur, arsenic, fluorine, chlorine and the like, and CaCO3And decomposing the carbonate. And (4) dust-collecting the tail gas and then desulfurizing.
(5) Uniformly adding the coal granules with carbon content of 60%, particle size of 2mm or more and less than 6mm and water content of 8% or less into a predecomposition furnace at a speed of 12t/h, controlling the air excess coefficient of the rotary kiln to be 0.75, wherein the rotary kiln is in a strong reducing atmosphere and the temperature in the kiln is 1310 ℃.
(6) After the materials are continuously fed for 5 hours, the zinc content of the lead-zinc oxide ore in the preheater is enriched to 32 percent, the feeding is stopped, the zinc-containing materials in the preheater are further reduced and volatilized, and the zinc oxide smoke is produced and enters a dust collecting system. The method adopts intermittent feeding production, feeds materials from a flue gas pipeline of a preheating unit, continuously feeds materials for 5 hours, stops feeding for 1 hour for volatilization reaction, and continuously feeds materials for 5 hours after lead-zinc oxide ore in a preheater is enriched to 32% in zinc content, so that high-grade zinc oxide smoke dust containing 55% in zinc is obtained by enriching and recycling.
(7) And (3) delivering the 1180 ℃ kiln slag produced by the rotary kiln to a grate cooler for recovering waste heat, and producing the kiln slag with the temperature of 95 ℃ and hot air with the temperature of 1000 ℃. The thermal efficiency of the grate cooler is more than or equal to 62 percent. The produced hot air is conveyed to the kiln head of the rotary kiln and the predecomposition furnace to be used as secondary combustion air, the residual hot air is used as a drying heat source for preparing coal powder and oxidizing the lead-zinc ore, and the rest of the hot air enters a waste heat boiler to generate power at a low temperature.
In the above way, the material obtained by adopting the method of the embodiment 1 has low zinc content, stable and continuous production process and good heat exchange effect. By adopting the mode of the embodiment 2, the process is continuous and stable, but the heat exchange effect is poor. By adopting the mode of the embodiment 3, the obtained smoke dust has the highest zinc content and the best heat exchange effect, but the production process is intermittent feeding and the process is discontinuous;
comparative example:
using a rotary kiln of the same processing capacity as in example 3, 1000t of the raw material component was Pb 2.26%; zn 9.73%; CaO 21.86 percent; SiO 22 28.34%； Al2O3 0.35 percent; 0.57 percent of MgO; and 4.34 percent of S (the oxidation rate of lead and zinc reaches 60 percent) of low-grade lead-zinc oxide ore is crushed and ball-milled in sequence. The granularity after crushing is less than or equal to 25mm, and accounts for 70 percent; ball milling the material to obtain a product with a particle size of less than or equal to 60 μm and a water content of less than or equal to 0.8%.
Mixing the crushed lead-zinc oxide ore and anthracite according to the weight ratio of 1: 0.45, the mixture is added into a rotary kiln, the temperature of the rotary kiln is controlled to be 1300 ℃, and the air coefficient is 0.75. The materials are preheated in the rotary kiln, and are reduced and volatilized to produce high-temperature kiln slag and flue gas. Taking out the kiln slag after water quenching; the smoke is cooled by a surface cooler and collected by a cloth bag, and then zinc oxide smoke is recovered. The method has the advantages that the kiln slag and the flue gas waste heat are not recycled, the coal consumption is up to 40-55%, the heat utilization rate is about 10%, continuous feeding and continuous discharging are adopted, the feeding amount of the lead-zinc oxide ore is 8t/h, and the zinc content in the collected zinc oxide smoke dust is 55%.
Through comparison, compared with a conventional reduction volatilization system only provided with a rotary kiln, the technical scheme of the application has the advantages that the coal consumption of unit ore is reduced by 55.5%, and the productivity is improved by 15.63 times.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.
Claims (10)
1. The utility model provides a lead zinc oxide ore resourceization innocent treatment system which characterized in that: the lead-zinc oxide ore recycling harmless treatment system comprises a preheating unit (1), a predecomposition furnace (2) and a rotary kiln (3), wherein lead-zinc oxide ore is added from the preheating unit (1); the preheating unit (1) is provided with a discharge port communicated to the pre-decomposition furnace (2); the flue gas outlet at the top of the pre-decomposition furnace (2) is communicated to the preheating unit (1), the pre-decomposition furnace (2) is provided with a pulverized coal feeding hole and a secondary air port, and the bottom of the pre-decomposition furnace (2) is communicated with the rotary kiln (3).
2. The lead-zinc oxide ore recycling harmless treatment system according to claim 1, characterized in that: the lead-zinc oxide ore recycling harmless treatment system also comprises a cooler (4); one end of the cooler (4) is connected with the kiln head of the rotary kiln (3), and the other end is provided with a cold slag discharge hole; secondary hot air generated by heat exchange of the cooler (4) is communicated to the pre-decomposition furnace (2) through a pipeline; and the kiln head of the rotary kiln (3) is provided with a hot air spray gun for providing air for combustion.
3. The lead-zinc oxide ore recycling harmless treatment system according to claim 1 or 2, characterized in that: in the preheating unit (1), the lead-zinc oxide ore is directly or indirectly contacted with the flue gas for preheating.
4. The lead-zinc oxide ore recycling harmless treatment system according to claim 3, characterized in that: the lead-zinc oxide ore can be continuously fed or intermittently fed.
5. The lead-zinc oxide ore recycling harmless treatment system according to claim 4, characterized in that: the temperature of the flue gas at the outlet of the preheating unit (1) is less than or equal to 400 ℃.
6. A method for recycling lead-zinc oxide ore without harm is characterized by comprising the following steps: the method for recycling the lead-zinc oxide ore into harmless resources comprises the following steps:
A. crushing, drying, grinding and homogenizing lead-zinc oxide ores;
B. adding lead-zinc oxide ore into a preheating unit for preheating;
C. under an oxidizing atmosphere, adding preheated lead and zinc oxide into a predecomposition furnace to complete predecomposition reaction and remove impurities such as sulfur, chlorine and the like; high-temperature flue gas generated by the pre-decomposition reaction is sent to the preheating unit in the step (2) to preheat lead-zinc oxide ore;
D. the intermediate material produced by the pre-decomposition furnace enters a rotary kiln, and reduction and volatilization of lead and zinc in lead-zinc oxide ores are completed in a reducing atmosphere;
E. and (4) recovering the waste heat of the high-temperature slag generated by the reduction reaction for pre-decomposition in the step C and wind for combustion in the step D.
7. The method for recycling the lead-zinc oxide ore into harmless resources according to claim 5, characterized in that: the preheating in the step B means that in the preheating unit, the lead-zinc oxide ore is directly or indirectly contacted with the high-temperature flue gas to preheat the lead-zinc oxide ore.
8. The method for recycling the lead-zinc oxide ore without harm according to claim 6, wherein the method comprises the following steps: and C, under the oxidizing atmosphere, the pre-decomposition temperature is more than or equal to 900 ℃.
9. The method for the resource harmless treatment of the lead-zinc oxide ores according to any one of claims 6 to 8, characterized in that: and D, under the reducing atmosphere, the reaction temperature is more than or equal to 1100 ℃.
10. The method for recycling the lead-zinc oxide ore without harm according to claim 6, wherein the method comprises the following steps: the lead-zinc oxide ore in the step A is one or more than two mixed ores of lead-zinc oxide ore, low-grade lead-zinc oxide ore or oxygen-sulfur mixed ore.
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| CN116159398A (en) * | 2023-03-01 | 2023-05-26 | 昆明理工大学 | Device and process for recycling low-grade lead-zinc mixed ore pyrometallurgy tail gas |
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