Aluminum electrolytic cell waste cathode carbon block treatment process
阅读说明：本技术 一种铝电解槽废阴极炭块处理工艺 (Aluminum electrolytic cell waste cathode carbon block treatment process ) 是由 林宏飞 杜建嘉 丘能 周郁文 周思宏 陈国宁 陈敏 慕俊豪 于 2021-06-16 设计创作，主要内容包括：本发明公开了一种铝电解槽废阴极炭块处理工艺及其系统,属于电解铝废弃物处理技术领域。本发明铝电解槽废阴极炭块处理的方法包括：将废阴极炭块粉料与碱液混合,高温高压浸出难溶氟化物并破氰,固液分离产出压浸渣和压浸液；压浸液沉氟产出氟化钙固体和破氰沉氟碱液,破氰沉氟碱液外送蒸发结晶产出含盐烧碱；压浸渣水浸后,固液分离产出水浸渣和含氟化钠的水浸液；水浸渣中和,产出中和渣；中和渣经洗涤后产出炭质料(主产品)；烟气收集。本发明实现了铝电解槽废阴极炭块无害化处理,碳、氟和钠碱资源得到回收,不仅可避免铝电解槽废阴极炭块对环境的危害,而且能实现废阴极炭块的资源化利用。(The invention discloses a treatment process and a treatment system for waste cathode carbon blocks of an aluminum electrolytic cell, and belongs to the technical field of treatment of waste of electrolytic aluminum. The method for treating the waste cathode carbon block of the aluminum electrolytic cell comprises the following steps: mixing the waste cathode carbon block powder with alkali liquor, leaching insoluble fluoride at high temperature and high pressure, breaking cyanogen, and carrying out solid-liquid separation to produce pressure leaching residue and pressure leaching liquid; the pressure leaching solution is used for fluorine precipitation to produce calcium fluoride solid and cyanogen-breaking fluorine-precipitating alkali liquor, and the cyanogen-breaking fluorine-precipitating alkali liquor is sent out for evaporation and crystallization to produce salt-containing caustic soda; after the press leaching residue is soaked in water, solid-liquid separation is carried out to produce water leaching residue and water leaching solution containing sodium fluoride; neutralizing the water leaching slag to produce neutralized slag; washing the neutralized slag to produce a carbon material (main product); and (4) collecting the flue gas. The method realizes the harmless treatment of the waste cathode carbon blocks of the aluminum electrolytic cell, recycles carbon, fluorine and sodium alkali resources, can avoid the harm of the waste cathode carbon blocks of the aluminum electrolytic cell to the environment, and can realize the resource utilization of the waste cathode carbon blocks.)
1. A treatment process of waste cathode carbon blocks of an aluminum electrolytic cell is characterized by comprising the following steps:
(1) pretreatment: crushing, grinding and screening the waste cathode carbon blocks to obtain 18-200 meshes of powder for later use;
(2) slurry preparation: injecting prepared alkali liquor into a slurry preparation tank, wherein the alkali liquor is prepared by mixing the following components in a liquid-solid ratio (1-10): 1, adding the powder obtained in the step (1), stirring at normal temperature to prepare slurry to obtain waste cathode carbon block slurry;
(3) pressure leaching and cyanogen breaking: adding cyanogen-breaking oxidant into the waste cathode carbon block slurry, adjusting temperature and pressure, leaching and breaking cyanogen from the waste cathode carbon block slurry to CN in the pressure leaching solution for sampling detection-The concentration is less than 1.0mg/L, then after the pressure leaching residue sample is fully washed by clear water and the fluorine concentration for the toxicity leaching test is less than 100mg/L, a pressure leaching filter press is adopted to carry out solid-liquid separation on the pressure leaching serous fluid, and pressure leaching residue and pressure leaching liquid are obtained;
(4) water leaching: putting the pressure leaching slag obtained in the step (3) into a water leaching reaction tank, adding water, stirring for reaction and leaching, sampling the leaching slag to detect toxicity, and performing solid-liquid separation on the reacted slurry by using a water leaching filter press after the fluorine concentration of a leaching slag toxicity leaching test is lower than 100mg/L to obtain a water leaching solution and water leaching slag;
(5) neutralizing: neutralizing the water leaching slag obtained in the step (4) by using inorganic acid until the pH value is 7-9, and performing solid-liquid separation on the neutralized slurry by using a filter press to obtain neutralized slag and neutralized liquid;
(6) washing: and (3) stirring and washing the neutralized residues with clear water, sampling and detecting that the content of soluble salts in the leached residues is lower than a control index, and then performing solid-liquid separation on the washing slurry by using a filter press to obtain a carbon material and a washing liquid.
2. The aluminum electrolytic cell waste cathode carbon block treatment process according to claim 1, wherein after the pressure leaching solution is recovered, soluble calcium salt is added under the conditions of normal temperature and stirring for fluorine precipitation, calcium fluoride and cyanogen-breaking fluorine-precipitating alkali liquor are produced after solid-liquid separation, solid calcium fluoride is recovered, and the cyanogen-breaking fluorine-precipitating alkali liquor is reused for high-temperature high-pressure leaching or evaporation concentration to produce caustic soda containing a small amount of soluble salt.
3. The aluminum electrolysis cell waste cathode carbon block treatment process according to claim 2, wherein the amount of calcium ions added in the added soluble calcium salt is 0.6-1.5 times of the reaction between calcium ions and fluorine ions, and the reaction time is 1-4 h.
4. The process for treating the waste cathode carbon block of the aluminum electrolytic cell as recited in claim 1, wherein in the step (2), the alkaline solution is prepared by mixing sodium hydroxide, process water and the pressure leaching solution obtained in the step (3).
5. The process as claimed in claim 1, wherein in the step (3), the temperature is 150-230 ℃, the pressure is 0.48-2.80MPa, and the cyanogen breaking time is 0.5-10 hours.
6. The aluminum electrolysis cell waste cathode carbon block treatment process according to claim 3, wherein in the step (4), the liquid-solid ratio of the water to the press leaching residue is (3-10): 1, the time of the reaction leaching is 0.5 to 10 hours.
7. The aluminum electrolysis cell waste cathode carbon block treatment process according to claim 1, wherein the cyanogen-breaking oxidant is one or more of chlorine dioxide, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, ozone and oxygen.
8. The treatment system for the aluminum electrolytic cell waste cathode carbon block treatment process according to claims 1 to 6, comprising a crushing and grinding module, a pressure leaching and filtering module, a fluorine and alkali precipitating and recovering module, a water leaching and filtering module, a neutralizing and filtering module, a washing and filtering module and a smoke collecting module, wherein the crushing and grinding module, the pressure leaching and filtering module, the fluorine and alkali precipitating and recovering module, the water leaching and filtering module, the neutralizing and filtering module and the washing and filtering module are sequentially connected, and the crushing and grinding module, the pressure leaching and filtering module, the fluorine and alkali precipitating and recovering module, the water leaching and filtering module, the neutralizing and filtering module and the washing and filtering module are respectively connected with the smoke collecting module.
Technical Field
The invention relates to the technical field of aluminum electrolysis overhaul slag treatment, in particular to a treatment process of waste cathode carbon blocks of an aluminum electrolysis cell.
Background
The aluminum electrolytic cell is a main device for metal aluminum smelting, the lining needs to be removed by major repair every 5 to 8 years, major repair slag is produced, and 15 to 20kg of major repair slag is discharged per ton of electrolytic aluminum raw aluminum. The aluminum electrolysis overhaul slag is mainly divided into two categories of waste cathode carbon blocks and waste refractory materials, the main toxic and harmful components are cyanide and soluble fluoride, and the aluminum electrolysis overhaul slag is listed in the national hazardous waste record in 2016.
In the aluminum electrolysis overhaul slag, the waste cathode carbon blocks account for about 55 percent, the waste refractory material accounts for about 45 percent, and the research direction of the aluminum electrolysis overhaul slag treatment is classified treatment due to different components of the waste cathode carbon blocks and the waste refractory material. The treatment process of the aluminum electrolysis overhaul slag comprises solidification stabilization landfill, wet detoxification, traditional pyrogenic process, flotation, pyrogenic process volatilization and other processes. The most common wet detoxification process is classified into acid decomposition, alkali decomposition, water leaching and the like. The solidification and stabilization landfill not only can not fully utilize resources, but also occupies valuable hazardous and useless landfill resources; the traditional pyrogenic process is incomplete in detoxification and cannot fully recover resources; the detoxification products of the existing wet process are difficult to utilize, resources are difficult to recycle, and the salt content of the wastewater is high; large investment for pyrogenic volatilization, high treatment cost and immature technology. The current technology is difficult to meet the requirements of resource recovery and increasingly strict environmental protection.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a treatment process of waste cathode carbon blocks of an aluminum electrolytic cell and a system using the process.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
a treatment process of waste cathode carbon blocks of an aluminum electrolytic cell comprises the following steps:
(1) pretreatment: crushing, grinding and screening the waste cathode carbon blocks to obtain 18-200 meshes of powder for later use;
(2) slurry preparation: injecting prepared alkali liquor into a slurry preparation tank, wherein the alkali liquor is prepared by mixing the following components in a liquid-solid ratio (1-10): 1, adding the powder obtained in the step (1), stirring at normal temperature to prepare slurry to obtain waste cathode carbon block slurry;
(3) pressure leaching and cyanogen breaking: adding cyanogen-breaking oxidant into the waste cathode carbon block slurry, adjusting temperature and pressure, leaching and breaking cyanogen from the waste cathode carbon block slurry to CN in the pressure leaching solution for sampling detection-The concentration is less than 1.0mg/L, then after the pressure leaching residue sample is fully washed by clear water and the fluorine concentration for the toxicity leaching test is less than 100mg/L, a pressure leaching filter press is adopted to carry out solid-liquid separation on the pressure leaching serous fluid, and pressure leaching residue and pressure leaching liquid are obtained;
(4) water leaching: putting the pressure leaching slag obtained in the step (3) into a water leaching reaction tank, adding water, stirring for reaction and leaching, sampling the leaching slag to detect toxicity, and performing solid-liquid separation on the reacted slurry by using a water leaching filter press after the fluorine concentration of a leaching slag toxicity leaching test is lower than 100mg/L to obtain a water leaching solution and water leaching slag;
(5) neutralizing: neutralizing the water leaching slag obtained in the step (4) by using inorganic acid until the pH value is 7-9, and performing solid-liquid separation on the neutralized slurry by using a filter press to obtain neutralized slag and neutralized liquid;
(6) washing: stirring and washing the neutralized slag by using clean water, performing sampling detection on the content of soluble salts in the leached slag to be lower than a control index, and performing solid-liquid separation on the washing slurry by using a filter press to obtain a carbon material and a washing liquid;
further, after the pressure leaching solution is recovered, soluble calcium salt is added under the conditions of normal temperature and stirring for fluorine precipitation, calcium fluoride and cyanogen-breaking fluorine-precipitating alkali liquor are produced after solid-liquid separation, solid calcium fluoride is recovered, and the cyanogen-breaking fluorine-precipitating alkali liquor is reused for high-temperature high-pressure leaching or evaporation concentration to produce caustic soda containing a small amount of soluble salt.
Furthermore, the amount of calcium ions added in the added soluble calcium salt is 0.6-1.5 times of the reaction time of the calcium ions and fluorine ions, and the reaction time is 1-4 h.
Further, in the step (2), the alkali liquor is prepared by mixing sodium hydroxide, process water and the pressure leaching solution obtained in the step (3).
Further, in the step (3), the temperature is 150-.
Further, in the step (4), the liquid-solid ratio of the water to the press leaching residue is (3-10): 1, the time of the reaction leaching is 0.5 to 10 hours.
Further, the cyanogen-breaking oxidant is one or more of chlorine dioxide, hydrogen peroxide, calcium hypochlorite, sodium hypochlorite, ozone and oxygen.
The utility model provides a processing system is handled to aluminium cell useless negative pole carbon block, includes that broken grinding module, pressure leach filter module, heavy fluorine and alkali recovery module, water logging filter module, neutralization filter module, washing filter module and collection cigarette module, broken grinding module, pressure leach filter module, heavy fluorine and alkali recovery module, water logging filter module, neutralization filter module, washing filter module connect gradually, and this broken grinding module, pressure leach filter module, heavy fluorine and alkali recovery module, water logging filter module, neutralization filter module, washing filter module are connected with collection cigarette module respectively.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
(1) the medicament consumption is less: the invention adopts the high-temperature and high-pressure alkaline leaching process, and can fully break cyanogen under the conditions of high temperature and high pressure, thereby greatly reducing the consumption of cyanogen breaking agents; the liquid-solid ratio of high-temperature and high-pressure alkaline leaching is low, and the conversion from the insoluble fluoride to the soluble fluoride can be realized by using lower sodium hydroxide;
(2) the product purity is high: the invention has less medicament dosage, mainly uses easily soluble chemical medicaments, has high solubility of reaction products, and can achieve higher product purity by simply washing the carbon material and the calcium fluoride;
(3) the resource recovery and utilization rate is high, and the carbon, fluorine and sodium alkali resources in the waste cathode carbon block are fully recycled.
(4) Is beneficial to continuous production: the invention treats the waste cathode carbon blocks of the aluminum electrolytic cell step by step, and is beneficial to controlling process indexes and realizing continuous production.
Drawings
FIG. 1 is a schematic process flow diagram of the present invention;
FIG. 2 is a schematic diagram of the processing system of the present invention.
1-a crusher, 2-a ball mill, 3-a vibrating screen, 4-an environmental smoke collecting hood, 5-a bag dust collector, 6-a slurry preparation tank, 7-a high-temperature high-pressure reaction kettle, 8-a pressure immersion pressure filtration pump, 9-a pressure immersion pressure filtration machine, 10-a pressure immersion filtration tank, 11-a pressure immersion filtrate pump, 12-a fluorine precipitation reaction tank, 13-a fluorine precipitation inclined plate settling tank, 14-a fluorine precipitation centrifugal settling machine, 15-a calcium fluoride pressure filtration pump, 16-a calcium fluoride pressure filtration machine, 17-a fluorine immersion filtration tank, 18-a fluorine immersion filtration pump, 19-a water immersion reaction tank, 20-a water immersion pressure filtration pump, 21-a water immersion pressure filtration machine, 22-a water immersion filtration tank, 23-a water immersion filtration pump, 24-a neutralization reaction tank, 25-a neutralization pressure filtration pump, 26-a neutralization pressure filtration machine, 27-a neutralization filtrate tank, 28-a neutralization filtrate pump, 29-a washing reaction tank, 30-a washing filter-pressing pump, 31-a washing filter press, 32-a washing filtrate tank and 33-a washing filtrate pump.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to preferred embodiments. It should be noted, however, that the numerous details set forth in the description are merely for the purpose of providing the reader with a thorough understanding of one or more aspects of the present invention, which may be practiced without these specific details.
The utility model provides an aluminium cell waste cathode carbon block processing system, includes that broken grinding module, pressure leach filter module, heavy fluorine and alkali recovery module, water logging filter module, neutralization filter module, washing filter module and collection cigarette module, broken grinding module, pressure leach filter module, heavy fluorine and alkali recovery module, water logging filter module, neutralization filter module, washing filter module connect gradually, and this broken grinding module, pressure leach filter module, heavy fluorine and alkali recovery module, water logging filter module, neutralization filter module, washing filter module are connected with collection cigarette module respectively.
The crushing and grinding module comprises a crusher 1, a ball mill 2 and a vibrating screen 3, a discharge port of the crusher 1 is communicated with a feed port of the ball mill 2, a discharge port of the ball mill 2 is communicated with a feed port of the vibrating screen 3, and a discharge port of the vibrating screen 3 is connected with the water immersion filtering module.
The pressure leaching filter module comprises a slurry preparation tank 6, a high-temperature high-pressure reaction kettle 7, a pressure leaching pressure filter pump 8, a pressure leaching pressure filter 9, a pressure leaching filtrate tank 10 and a pressure leaching filtrate pump 11, wherein a feed inlet of the slurry preparation tank 6 is communicated with a discharge outlet of a vibrating screen 3, a feed inlet of the high-temperature high-pressure reaction kettle 7 is communicated with a discharge outlet of the slurry preparation tank 6, a discharge outlet of the high-temperature high-pressure reaction kettle 7 is communicated with a feed inlet of the pressure leaching pressure filter 9 through the pressure leaching pressure filter pump 8, a liquid outlet of the pressure leaching pressure filter 9 is communicated with the pressure leaching filtrate tank 10, the pressure leaching filtrate tank 10 is respectively communicated with the slurry preparation tank 6 through the pressure leaching filtrate pump 11, and the pressure leaching filtrate tank 10 is connected with a fluorine precipitation and alkali recovery module through the pressure leaching filtrate pump 11.
The fluorine and alkali precipitation recovery module comprises a fluorine precipitation reaction tank 12, a fluorine precipitation inclined plate settling tank 13, a fluorine precipitation centrifugal settling machine 14, a calcium fluoride filter press pump 15, a calcium fluoride filter press 16, a fluorine precipitation filtrate tank 17 and a fluorine precipitation filtrate pump 18, the feed inlet of the fluorine precipitation reaction tank 12 is communicated with a pressure leaching filtrate pump 11, the discharge outlet of the fluorine precipitation reaction tank 12 is communicated with the feed inlet of a fluorine precipitation inclined plate settling tank 13, the discharge hole of the fluorine-settling sloping plate settling tank 13 is communicated with the feed hole of a fluorine-settling centrifugal settling machine 14, the discharge hole of the fluorine-precipitating centrifugal settler 14 is communicated with the feed inlet of a calcium fluoride filter press 16 through a calcium fluoride filter press pump 15, the liquid outlets of the fluorine-settling inclined plate settling tank 13, the fluorine-settling centrifugal settling machine 14 and the calcium fluoride filter press 16 are all communicated with the liquid inlet of a fluorine-settling filtrate tank 17, the liquid outlet of the fluorine precipitation filtrate tank 17 is connected with the slurry preparation tank 6 and an external caustic soda evaporation recovery device through a fluorine precipitation filtrate pump 18.
The water leaching filter module comprises a water leaching reaction tank 19, a water leaching filter pressing pump 20, a water leaching filter pressing machine 21, a water leaching filtrate tank 22 and a water leaching filtrate pump 23, wherein a feed inlet of the water leaching reaction tank 19 is communicated with a discharge outlet of the pressure leaching filter pressing machine 9, the discharge outlet of the water leaching reaction tank 19 is communicated with the feed inlet of the water leaching filter pressing machine 21 through the water leaching filter pressing pump 20, a liquid outlet of the water leaching filter pressing machine 21 is communicated with a liquid inlet of the water leaching filtrate tank 22, a liquid outlet of the water leaching filtrate tank 22 is communicated with the feed inlet of the pressure leaching reaction tank through the water leaching filtrate pump 23, and the water leaching filtrate tank 22 is connected with the neutralization module through the water leaching filtrate pump 23.
The neutralization filtering module comprises a neutralization reaction tank 24, a neutralization filter press 25, a neutralization filter press 26, a neutralization filtrate tank 27 and a neutralization filtrate pump 28, wherein a feed inlet of the neutralization reaction tank 24 is communicated with a discharge outlet of the water immersion filter press 21, a discharge outlet of the neutralization reaction tank 24 is communicated with a feed inlet of the neutralization filter press 26 through the neutralization filter press 25, a liquid outlet of the neutralization filter press 26 is communicated with a liquid inlet of the neutralization filtrate tank 27, and a liquid outlet of the neutralization filtrate tank 27 is respectively communicated with a feed inlet of the water immersion filtrate tank 22 and a feed inlet of the neutralization reaction tank 24 through the neutralization filtrate pump 28.
The washing and filtering module comprises a washing reaction tank 29, a washing filter-pressing pump 30, a washing filter press 31, a washing filtrate tank 32 and a washing filtrate pump 33, wherein a feed inlet of the washing reaction tank 29 is communicated with a discharge outlet of the neutralization filter press 26, a discharge outlet of the washing reaction tank 29 is communicated with a feed inlet of the washing filter press 31 through the washing filter-pressing pump 30, a liquid outlet of the washing filter press 31 is communicated with a liquid inlet of the washing filtrate tank 32, and a liquid outlet of the washing filtrate tank 32 is respectively communicated with a feed inlet of the neutralization filtrate tank 27 and a feed inlet of the washing reaction tank 29 through the washing filtrate pump 33.
The smoke collecting module comprises two environment smoke collecting hoods 4, a bag-type dust collector 5 and smoke collecting pipelines, wherein the two environment smoke collecting hoods 4 are respectively arranged above the crusher 1 and the ball mill 2, the two environment smoke collecting hoods 4 are both communicated with the bag-type dust collector 5, and a discharge port of the bag-type dust collector 5 is communicated with an external smoke treatment system through an environment smoke collecting main pipe; the slurry preparation tank 6, the fluorine precipitation reaction tank 12, the water immersion reaction tank 19, the neutralization reaction tank 24 and the washing reaction tank 29 are provided with top covers and are communicated with an environmental smoke collection main pipe through smoke collection branch pipes; the high-temperature high-pressure reaction kettle 7 is operated in a sealing mode, and the top of the high-temperature high-pressure reaction kettle 7 is communicated with the environment smoke collection main pipe through a smoke discharge branch pipe.
Examples 1 to 3 are specific operations for carrying out the treatment by the above-mentioned aluminum electrolytic cell waste cathode carbon block treatment system.
Example 1
The aluminum electrolytic cell waste cathode carbon block treatment steps are as follows:
A. pretreatment: crushing the waste cathode carbon blocks by using a crusher 1, feeding the crushed waste cathode carbon blocks with the particle size less than 20mm into a ball mill 2, carrying out ball milling for 2 hours, feeding the ball-milled powder into a vibrating screen 3, sieving the powder by using a screen with the specification of 2mm, and feeding qualified undersize into a slurry preparation tank 6; returning the screened residues and the powder material unqualified in the spot check to the ball mill 2 for continuous ball milling; crushing, grinding and screening the waste cathode carbon blocks to obtain powder with the granularity requirement of 160-180 meshes;
B. slurry preparation: adding sodium hydroxide, process water, pressure immersion liquid conveyed by a pressure immersion liquid filter pump 11 and defluorination pressure immersion liquid conveyed by a defluorination liquid filter pump 18 into a slurry preparation tank, preparing liquid according to the concentration of NaOH of 35g/L, adding qualified waste cathode carbon block powder obtained by ball milling in the step A according to the liquid-solid ratio of 3:1, stirring and preparing slurry at normal temperature to produce waste cathode carbon block slurry;
C. pressure leaching and cyanogen breaking: the waste cathode carbon block slurry prepared by the slurry preparation tank 6 automatically flows into the high-temperature high-pressure reaction kettle 7, high-pressure oxygen is introduced, and leaching and cyanogen breaking are carried out for 2 hours at the temperature of 185 ℃ and the pressure of 1.12 MPa; sampling to test for CN in pressure immersion liquid-The concentration is less than 1.0mg/L, the fluorine concentration of the pressure leaching residue sample subjected to toxicity leaching test after being fully washed by clear water is less than 100mg/L, the high-temperature high-pressure leaching slurry is conveyed to a pressure leaching filter machine 9 through a pressure leaching pressure filter pump 8 for pressure filtration to obtain pressure leaching residue and pressure leaching filtrate, and the pressure leaching residue and the pressure leaching filtrate are subjected to pressure filtrationThe slag is sent to a water leaching reaction tank 19, and pressure leaching filtrate automatically flows into a pressure leaching filtrate tank 10 and then is sent to a fluorine precipitation reaction tank 12 for fluorine precipitation through a pressure leaching filtrate pump 11 or is sent to a slurry preparation tank 6 for recycling;
D. water leaching: putting the pressure leaching slag produced by the pressure leaching filter press 9 into a water leaching reaction tank 19, stirring and leaching, wherein the liquid-solid ratio of a water leaching solution to the pressure leaching slag is 6:1, the reaction time is 2 hours, sampling and detecting the toxicity of the leaching slag, and after the fluorine concentration of a leaching slag toxicity leaching test is lower than 100mg/L, performing pressure filtration on a water leaching slurry conveyer belt water leaching filter press 21 through a water leaching filter press pump 20 to produce a water leaching filtrate and water leaching slag, conveying the water leaching slag to a neutralization reaction tank 24, automatically leaching the water leaching filtrate into a water leaching filtrate tank 22, and conveying the water leaching filtrate to the pressure leaching filtrate tank 10 or the water leaching filtrate tank 19 for recycling through a water leaching filtrate pump 23;
E. neutralizing: conveying the water leaching slag produced by the water leaching filter press 21 to a neutralization reaction tank 24, adding hydrochloric acid for neutralization, stirring at normal temperature, conveying the neutralized slurry to a neutralization filter press 26 through a neutralization filter press pump 25 for filter pressing after the pH value of the slurry is stabilized at 7-9 for more than 1 hour, producing neutralized filtrate and neutralized slag, conveying the neutralized slag to a washing reaction tank 29, automatically flowing the neutralized filtrate into a neutralized filtrate tank 27, and conveying the neutralized filtrate to a water leaching filtrate tank 22 or a neutralized reaction tank 24 through a neutralized filtrate pump 28 for recycling;
F. washing: conveying neutralized slag produced by the water neutralization filter press 26 to a washing reaction tank 29, stirring and washing clean water at normal temperature, after sampling detection is performed on the content of soluble salts in the leached slag to be lower than a control index, conveying washing slurry to a washing filter press 31 through a washing filter press pump 30 for filter pressing to produce washing filtrate and washing slag, automatically flowing the washing filtrate into a washing filtrate tank 32, conveying the washing filtrate to the neutralized filtrate tank 27 or the washing reaction tank 29 through a washing filtrate pump 33 for recycling, and detecting the content of fluorine in a toxicity leaching test to be less than 100mg/L, wherein CN is CN-<5mg/L washing slag is a carbon material which is sold as a product;
G. and (3) recovering calcium fluoride: stirring the pressure leaching solution from a pressure leaching filtrate pump 11 in a fluorine precipitation reaction tank 12 at normal temperature, adding calcium chloride according to 1.05 times (calcium ion meter) of the theoretical dosage of the reaction of calcium ions and fluorine ions to carry out fluorine precipitation treatment on the pressure leaching solution, wherein the reaction time is 1h, the fluorine precipitation slurry automatically flows into a fluorine precipitation inclined plate settling tank 13 for settling, then the bottom slurry is put into a fluorine precipitation centrifugal settling machine 14 for centrifugal separation, the slurry produced by the centrifugal settling machine 14 is conveyed to a calcium fluoride filter press 16 by a calcium fluoride filter press pump 15 for filter pressing, the produced calcium fluoride (product), the fluorine precipitation filtrate generated by the fluorine precipitation inclined plate settling tank 13 and the centrifugal settling machine 14 automatically flows into a fluorine precipitation filtrate tank 17, and the fluorine precipitation filtrate is conveyed to a slurry preparation tank 6 for recycling by a fluorine precipitation filtrate pump 18 or conveyed to the outside by the fluorine precipitation filtrate pump 18 for evaporation and recovery of caustic soda;
H. collecting flue gas: after being collected by a smoke collecting hood 4, the dust-containing smoke generated by the crusher 1, the ball mill 2 and the vibrating screen 3 is sent to a bag-type dust remover 5 for dust removal treatment, and the smoke subjected to the dust removal treatment by the bag-type dust remover 5 is converged into a smoke main pipe; the equipment such as the slurry preparation tank 6, the high-temperature high-pressure reaction kettle 7, the fluorine precipitation reaction tank 12, the water immersion reaction tank 19, the neutralization reaction tank 24 and the washing reaction tank 29 introduces flue gas into the flue gas main pipe through the flue gas suction ports at the tops of the equipment, joins with the flue gas subjected to dust removal treatment by the bag-type dust remover 5, and is discharged after reaching the standard after being sent to an external flue gas treatment system for treatment.
I. Treatment effect;
the components of the waste cathode carbon block of the aluminum electrolytic cell before treatment are as follows:
composition (I)
C
NaF
CaF2
Na3AlF6
CaO
％
69.35
15.55
0.54
2.94
1.55
Composition (I)
MgO
SiO2
Fe
Na2O
CN-
％
0.87
4.96
1.18
2.372
0.08
The method is characterized in that leaching toxicity and corrosivity of carbon materials (main products) are identified, the carbon materials are judged to reach the standard, and detection data and judgment are shown in the following table:
in the above table, the leaching toxicity of the sample is detected according to the sulfuric acid-nitric acid method of the leaching toxicity leaching method of HJT 299-2007 solid waste, and in the leaching toxicity detection result, F-The concentration is identified according to the limit value of I-type industrial solid waste, and the cyanogen is identified according to the limit value specified in GB 5085.3-2007 identification standard leaching toxicity identification of hazardous waste; corrosivity leachate was prepared according to "GB/T15555.12-1995 standard for identifying corrosivity of solid wastes" glass electrode method, and identified according to Standard limits of "GB 5085.1 Standard for identifying corrosivity of hazardous wastes" standardOtherwise.
According to the general rule of GB 5085.7-2019 hazardous waste identification Standard 6.2, the solid waste generated in the hazardous waste utilization process with the toxic hazardous characteristic is identified to be no longer hazardous and not to be hazardous waste, and the main product carbon material in the case is no longer hazardous and can be sold as a product. The byproduct saline-alkali solution containing fluorine and cyanogen has qualified indexes and no toxic and harmful components, and is reused for desulfurization.
The consumption of the refractory auxiliary material and the product yield per 100 tons of the waste refractory in this case are shown in the following table:
the cyanide breaking agent is not digested in the case.
Example 2
Example 2 aluminum cell waste cathode carbon block treatment steps are as follows:
A. pretreatment: crushing the waste cathode carbon blocks by using a crusher 1, feeding the crushed waste cathode carbon blocks with the particle size less than 20mm into a ball mill 2, carrying out ball milling for 2 hours, feeding the ball-milled powder into a vibrating screen 3, sieving the powder by using a screen with the specification of 2mm, and feeding qualified undersize into a slurry preparation tank 6; returning the screened residues and the powder material unqualified in the spot check to the ball mill 2 for continuous ball milling; crushing, grinding and screening the waste cathode carbon blocks to obtain powder with the granularity requirement of 160-180 meshes;
B. slurry preparation: adding sodium hydroxide, process water, pressure immersion liquid conveyed by a pressure immersion liquid filter pump 11 and defluorination pressure immersion liquid conveyed by a defluorination liquid filter pump 18 into a slurry preparation tank, preparing liquid according to the concentration of NaOH of 35g/L, adding qualified waste cathode carbon block powder obtained by ball milling in the step A according to the liquid-solid ratio of 3:1, stirring and preparing slurry at normal temperature to produce waste cathode carbon block slurry;
C. pressure leaching and cyanogen breaking: the waste cathode carbon block slurry prepared by the slurry preparation tank 6 automatically flows into the high-temperature high-pressure reaction kettle 7 and is added according to 3.0 times of the theoretical dosageSodium hypochlorite (with the effective chlorine content of 10 percent) is leached and cyanogen is broken for 2 hours under the conditions of the temperature of 185 ℃ and the pressure of 1.12 MPa; sampling to test for CN in pressure immersion liquid-The concentration is less than 1.0mg/L, after the pressure leaching residue sample is fully washed by clear water and the fluorine concentration for toxicity leaching test is less than 100mg/L, high-temperature and high-pressure leaching slurry is conveyed to a pressure leaching filter press 9 through a pressure leaching filter pump 8 for filter pressing to obtain pressure leaching residue and pressure leaching liquid, the pressure leaching residue is conveyed to a water leaching reaction tank 19, the pressure leaching liquid automatically flows into a pressure leaching liquid tank 10 and then is conveyed to a fluorine precipitation reaction tank 12 through a pressure leaching liquid pump 11 for fluorine precipitation, or is conveyed to a slurry preparation tank 6 for recycling;
D. water leaching: putting the pressure leaching slag produced by the pressure leaching filter press 9 into a water leaching reaction tank 19, stirring and leaching, wherein the liquid-solid ratio of a water leaching solution to the pressure leaching slag is 6:1, the reaction time is 3 hours, sampling and detecting the toxicity of the leaching slag, and after the fluorine concentration of a leaching slag toxicity leaching test is lower than 100mg/L, performing pressure filtration on a water leaching slurry conveyer belt water leaching filter press 21 through a water leaching filter press pump 20 to produce a water leaching filtrate and water leaching slag, conveying the water leaching slag to a neutralization reaction tank 24, automatically leaching the water leaching filtrate into a water leaching filtrate tank 22, and conveying the water leaching filtrate to the pressure leaching filtrate tank 10 or the water leaching filtrate tank 19 for recycling through a water leaching filtrate pump 23;
E. neutralizing: conveying the water leaching slag produced by the water leaching filter press 21 to a neutralization reaction tank 24, adding hydrochloric acid for neutralization, stirring at normal temperature, conveying the neutralized slurry to a neutralization filter press 26 through a neutralization filter press pump 25 for filter pressing after the pH value of the slurry is stabilized at 7-9 for more than 1 hour, producing neutralized filtrate and neutralized slag, conveying the neutralized slag to a washing reaction tank 29, automatically flowing the neutralized filtrate into a neutralized filtrate tank 27, and conveying the neutralized filtrate to a water leaching filtrate tank 22 or a neutralized reaction tank 24 through a neutralized filtrate pump 28 for recycling;
F. washing: conveying neutralized slag produced by the water neutralization filter press 26 to a washing reaction tank 29, stirring and washing with clean water at normal temperature, after sampling detection that the content of soluble salts in the leached slag is lower than a control index, conveying washing slurry to a washing filter press 31 through a washing filter press pump 30 for filter pressing to produce washing filtrate and washing slag, automatically flowing the washing filtrate into a washing filtrate tank 32, conveying the washing filtrate to the neutralized filtrate tank 27 or the washing reaction tank 29 through a washing filtrate pump 33 for recycling, and detecting that the content of fluorine is less than 100m in a toxicity leaching testg/L，CN-<5mg/L washing slag is a carbon material which is sold as a product;
G. and (3) recovering calcium fluoride: stirring the pressure leaching solution from a pressure leaching filtrate pump 11 in a fluorine precipitation reaction tank 12 at normal temperature, adding calcium chloride according to 1.05 times (calcium ion meter) of the theoretical dosage of the reaction of calcium ions and fluorine ions to carry out fluorine precipitation treatment on the pressure leaching solution, wherein the reaction time is 2h, the fluorine precipitation slurry automatically flows into a fluorine precipitation inclined plate settling tank 13 for settling, then the bottom slurry is put into a fluorine precipitation centrifugal settling machine 14 for centrifugal separation, the slurry produced by the centrifugal settling machine 14 is conveyed to a calcium fluoride filter press 16 by a calcium fluoride filter press pump 15 for filter pressing to produce calcium fluoride (product), the fluorine precipitation filtrate produced by the fluorine precipitation inclined plate settling tank 13 and the centrifugal settling machine 14 automatically flows into a fluorine precipitation filtrate tank 17, and the fluorine precipitation filtrate is conveyed to a slurry preparation tank 6 for recycling by a fluorine precipitation filtrate pump 18 or conveyed to the outside by the fluorine precipitation filtrate pump 18 for evaporation and recovery of caustic soda;
H. collecting flue gas: after being collected by a smoke collecting hood 4, the dust-containing smoke generated by the crusher 1, the ball mill 2 and the vibrating screen 3 is sent to a bag-type dust remover 5 for dust removal treatment, and the smoke subjected to the dust removal treatment by the bag-type dust remover 5 is converged into a smoke main pipe; the equipment such as the slurry preparation tank 6, the high-temperature high-pressure reaction kettle 7, the fluorine precipitation reaction tank 12, the water immersion reaction tank 19, the neutralization reaction tank 24 and the washing reaction tank 29 introduces flue gas into the flue gas main pipe through the flue gas suction ports at the tops of the equipment, joins with the flue gas subjected to dust removal treatment by the bag-type dust remover 5, and is discharged after reaching the standard after being sent to an external flue gas treatment system for treatment.
I. Treatment effect;
the components of the waste cathode carbon block of the aluminum electrolytic cell before treatment are as follows:
the leaching toxicity and corrosivity of the carbon material (main product) are identified, the carbon material is judged to reach the standard, and the detection data and the judgment result are shown in the following table:
in the above table, the leaching toxicity of the sample is detected according to the sulfuric acid-nitric acid method of the leaching toxicity leaching method of HJT 299-2007 solid waste, and in the leaching toxicity detection result, F-The concentration is identified according to the limit value of I-type industrial solid waste, and the cyanogen is identified according to the limit value specified in GB 5085.3-2007 identification standard leaching toxicity identification of hazardous waste; corrosivity leachate was prepared according to the "GB/T15555.12-1995 glass electrode method for identifying corrosivity of solid wastes", and identified according to the standard limits of the "GB 5085.1 Standard for identifying corrosivity of hazardous wastes".
According to the general rule of GB 5085.7-2019 hazardous waste identification Standard 6.2, the solid waste generated in the hazardous waste utilization process with toxic hazardous characteristics is identified to be no longer hazardous and not hazardous waste, the main product carbon material in the case is no longer hazardous waste and can be sold as a product, and the byproduct salt and alkali-containing liquid fluorine and cyanogen is qualified in index and free of toxic and harmful components and is reused for desulfurization.
The consumption of the refractory auxiliary material and the product yield per 100 tons of the waste refractory in this case are shown in the following table:
the process and the treatment system are adopted to treat the waste cathode carbon blocks of the aluminum electrolytic cell, so that the carbon in the waste cathode carbon blocks can be recycled, the resources such as fluorine, Na and the like in the waste cathode carbon blocks can be recycled, and the comprehensive utilization of the resources is realized.
Example 3
The treatment steps of the waste refractory materials of the aluminum electrolytic cell are as follows:
A. pretreatment: crushing the waste cathode carbon blocks by using a crusher 1, feeding the crushed waste cathode carbon blocks with the particle size less than 20mm into a ball mill 2, carrying out ball milling for 2 hours, feeding the ball-milled powder into a vibrating screen 3, sieving the powder by using a screen with the specification of 2mm, and feeding qualified undersize into a slurry preparation tank 6; returning the screened residues and the powder material unqualified in the spot check to the ball mill 2 for continuous ball milling; crushing, grinding and screening the waste cathode carbon blocks to obtain powder with the granularity requirement of 160-180 meshes;
B. slurry preparation: adding sodium hydroxide, process water, pressure immersion liquid conveyed by a pressure immersion liquid filter pump 11 and defluorination pressure immersion liquid conveyed by a defluorination liquid filter pump 18 into a slurry preparation tank, preparing liquid according to the concentration of NaOH of 35g/L, adding qualified waste cathode carbon block powder obtained by ball milling in the step A according to the liquid-solid ratio of 3:1, stirring and preparing slurry at normal temperature to produce waste cathode carbon block slurry;
C. pressure leaching and cyanogen breaking: the waste cathode carbon block slurry prepared by the slurry preparation tank 6 automatically flows into a high-temperature high-pressure reaction kettle 7, sodium hypochlorite (with the effective chlorine content of 10%) is added according to 3 times of the theoretical amount, and leaching and cyanogen breaking are carried out for 2 hours at the temperature of 185 ℃ and the pressure of 1.12 MPa; sampling to test for CN in pressure immersion liquid-The concentration is less than 1.0mg/L, after the pressure leaching residue sample is fully washed by clear water and the fluorine concentration for toxicity leaching test is less than 100mg/L, high-temperature and high-pressure leaching slurry is conveyed to a pressure leaching filter press 9 through a pressure leaching filter pump 8 for filter pressing to obtain pressure leaching residue and pressure leaching liquid, the pressure leaching residue is conveyed to a water leaching reaction tank 19, the pressure leaching liquid automatically flows into a pressure leaching liquid tank 10 and then is conveyed to a fluorine precipitation reaction tank 12 through a pressure leaching liquid pump 11 for fluorine precipitation, or is conveyed to a slurry preparation tank 6 for recycling;
D. water leaching: putting the pressure leaching slag produced by the pressure leaching filter press 9 into a water leaching reaction tank 19, stirring and leaching, wherein the liquid-solid ratio of a water leaching solution to the pressure leaching slag is 6:1, the reaction time is 3 hours, sampling and detecting the toxicity of the leaching slag, and after the fluorine concentration of a leaching slag toxicity leaching test is lower than 100mg/L, performing pressure filtration on a water leaching slurry conveyer belt water leaching filter press 21 through a water leaching filter press pump 20 to produce a water leaching filtrate and water leaching slag, conveying the water leaching slag to a neutralization reaction tank 24, automatically leaching the water leaching filtrate into a water leaching filtrate tank 22, and conveying the water leaching filtrate to the pressure leaching filtrate tank 10 or the water leaching filtrate tank 19 for recycling through a water leaching filtrate pump 23;
E. neutralizing: conveying the water leaching slag produced by the water leaching filter press 21 to a neutralization reaction tank 24, adding hydrochloric acid for neutralization, stirring at normal temperature, conveying the neutralized slurry to a neutralization filter press 26 through a neutralization filter press pump 25 for filter pressing after the pH value of the slurry is stabilized at 7-9 for more than 1 hour, producing neutralized filtrate and neutralized slag, conveying the neutralized slag to a washing reaction tank 29, automatically flowing the neutralized filtrate into a neutralized filtrate tank 27, and conveying the neutralized filtrate to a water leaching filtrate tank 22 or a neutralized reaction tank 24 through a neutralized filtrate pump 28 for recycling;
F. washing: conveying neutralized slag produced by the water neutralization filter press 26 to a washing reaction tank 29, stirring and washing with clean water at normal temperature, after sampling detection that the content of soluble salts in the leached slag is lower than a control index, conveying washing slurry to a washing filter press 31 through a washing filter press pump 30 for filter pressing to produce washing filtrate and washing slag, automatically flowing the washing filtrate into a washing filtrate tank 32, conveying the washing filtrate to the neutralized filtrate tank 27 or the washing reaction tank 29 through a washing filtrate pump 33 for recycling, and detecting that the content of fluorine is less than 100mg/L in a toxicity leaching test, wherein CN-<5mg/L washing slag is a carbon material which is sold as a product;
G. and (3) recovering calcium fluoride: stirring the pressure leaching solution from a pressure leaching filtrate pump 11 in a fluorine precipitation reaction tank 12 at normal temperature, adding calcium chloride according to 1.05 times (calcium ion meter) of the theoretical dosage of the reaction of calcium ions and fluorine ions to carry out fluorine precipitation treatment on the pressure leaching solution, wherein the reaction time is 2h, the fluorine precipitation slurry automatically flows into a fluorine precipitation inclined plate settling tank 13 for settling, then the bottom slurry is put into a fluorine precipitation centrifugal settling machine 14 for centrifugal separation, the slurry produced by the centrifugal settling machine 14 is conveyed to a calcium fluoride filter press 16 by a calcium fluoride filter press pump 15 for filter pressing to produce calcium fluoride (product), the fluorine precipitation filtrate produced by the fluorine precipitation inclined plate settling tank 13 and the centrifugal settling machine 14 automatically flows into a fluorine precipitation filtrate tank 17, and the fluorine precipitation filtrate is conveyed to a slurry preparation tank 6 for recycling by a fluorine precipitation filtrate pump 18 or conveyed to the outside by the fluorine precipitation filtrate pump 18 for evaporation and recovery of caustic soda;
H. collecting flue gas: after being collected by a smoke collecting hood 4, the dust-containing smoke generated by the crusher 1, the ball mill 2 and the vibrating screen 3 is sent to a bag-type dust remover 5 for dust removal treatment, and the smoke subjected to the dust removal treatment by the bag-type dust remover 5 is converged into a smoke main pipe; the equipment such as the slurry preparation tank 6, the high-temperature high-pressure reaction kettle 7, the fluorine precipitation reaction tank 12, the water immersion reaction tank 19, the neutralization reaction tank 24 and the washing reaction tank 29 introduces flue gas into the flue gas main pipe through the flue gas suction ports at the tops of the equipment, joins with the flue gas subjected to dust removal treatment by the bag-type dust remover 5, and is discharged after reaching the standard after being sent to an external flue gas treatment system for treatment.
I. Treatment effect;
the components of the waste cathode carbon block of the aluminum electrolytic cell before treatment are as follows:
composition (I)
C
NaF
CaF2
Na3AlF6
CaO
％
66.12
16.02
1.65
3.62
1.66
Composition (I)
MgO
SiO2
Fe
Na2O
CN-
％
1.06
4.81
1.26
2.49
0.09
The leaching toxicity and corrosivity of the carbon material (main product) are identified, the carbon material is judged to reach the standard, and the detection data and the judgment result are shown in the following table:
in the above table, the leaching toxicity of the sample is detected according to the sulfuric acid-nitric acid method of the leaching toxicity leaching method of HJT 299-2007 solid waste, and in the leaching toxicity detection result, F-The concentration is identified according to the limit value of I-type industrial solid waste, and the cyanogen is identified according to the limit value specified in GB 5085.3-2007 identification standard leaching toxicity identification of hazardous waste; corrosivity leachate was prepared according to the "GB/T15555.12-1995 glass electrode method for identifying corrosivity of solid wastes", and identified according to the standard limits of the "GB 5085.1 Standard for identifying corrosivity of hazardous wastes".
According to the general rule of GB 5085.7-2019 hazardous waste identification Standard 6.2, the solid waste generated in the hazardous waste utilization process with toxic hazardous characteristics is identified to be no longer hazardous and not hazardous waste, the main product carbon material in the case is no longer hazardous waste and can be sold as a product, and the byproduct salt and alkali-containing liquid fluorine and cyanogen is qualified in index and free of toxic and harmful components and is reused for desulfurization.
The consumption of the refractory auxiliary material and the product yield per 100 tons of the waste refractory in this case are shown in the following table:
the process and the treatment system are adopted to treat the waste cathode carbon blocks of the aluminum electrolytic cell, so that the carbon in the waste cathode carbon blocks can be recycled, the resources such as fluorine, Na and the like in the waste cathode carbon blocks can be recycled, and the comprehensive utilization of the resources is realized.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.