CN114436236A - Method for purifying cracking carbon black and by-producing fluosilicic acid - Google Patents
Method for purifying cracking carbon black and by-producing fluosilicic acid Download PDFInfo
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- CN114436236A CN114436236A CN202011231767.7A CN202011231767A CN114436236A CN 114436236 A CN114436236 A CN 114436236A CN 202011231767 A CN202011231767 A CN 202011231767A CN 114436236 A CN114436236 A CN 114436236A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
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Abstract
The invention relates to the field of recycling of solid waste resources, and discloses a method for purifying cracked carbon black and producing fluosilicic acid as a byproduct, which comprises the following steps: (1) carrying out first contact on the cracking carbon black and an acid solution, and then carrying out solid-liquid separation to obtain a first filtrate and first carbon black containing a silicon compound; (2) carrying out second contact on the first carbon black containing the silicon compound and a solution containing fluosilicic acid, and then carrying out solid-liquid separation to obtain second carbon black and a second filtrate; (3) and purifying the second filtrate to obtain the fluosilicic acid. The method provided by the invention can reduce the ash content in the cracked carbon black and simultaneously produce the fluosilicic acid byproduct, thereby fully realizing the effective utilization of resources.
Description
Technical Field
The invention relates to the technical field of solid waste resource utilization, in particular to a method for purifying cracking carbon black and by-producing fluosilicic acid.
Background
With the rapid development of social economy in China, the rapid growth and the large popularization of people on automobile consumption are greatly promoted. According to statistics, the motor vehicle holding amount in the last half of 2019 reaches 3.4 hundred million vehicles, wherein 2652 million vehicles newly registered in China in 2018. The tyre is the only consumable part of the vehicle in contact with the ground, and the production consumption of the tyre is closely related to the vehicle industry. In TOP 75 enterprises of global tires, a batch of national industries such as the oriented sun, exquisite and triangular industries, etc. emerge in China, occupy 45% of seats, and are famous and genuine tire major countries. The service life of a car tire is 5-8 years or 6-8 ten thousand miles, and the discarded tires contain a large amount of rubber, steel wires, white carbon black and carbon black, and additives such as organic accelerators, zinc sulfide, aluminum oxide, calcium carbonate and pottery clay. The annual output of the waste tires in China reaches more than 1300 million tons, and the waste tires still increase at the speed of 8% -10% per year. With the increasing scrappage of waste tires, the processing pressure is higher and higher. At present, four waste tire treatment methods are mainly adopted, namely, repair, regeneration, incineration and pyrolysis, wherein the former two methods are influenced by the self state of the tire in the disposal process to cause the condition of unstable quality of retreaded tires or regenerated rubber powder, and the third method is easy to generate toxic tail gas in the incineration process to cause secondary pollution, so that the pollution problem of the waste tires cannot be fundamentally solved. Correspondingly, the fourth pyrolysis method is a method for carrying out heat treatment on organic components in the tires under the anoxic condition, has the characteristics of low energy consumption, small pollution, high economic benefit and the like, and is beneficial to large-scale regeneration of tire resources.
The tire pyrolysis process technology is that the waste tire is cut into small blocks of 3-5cm, and then the small blocks are placed into a sealed tunnel kiln to be subjected to heat treatment for half an hour at the temperature of 400-. Pyrolysis gas obtained by pyrolysis is generally directly returned to the furnace to be used as fuel required by tire pyrolysis. The pyrolysis oil can be directly or further processed into heavy oil, fuel oil or other chemicals; the steel wire can be recycled after magnetic separation. The cracking carbon black mainly contains reinforcing carbon black with various grades, filler carbon black, other carbon black generated by organic matter decomposition in the pyrolysis process, and various additives added in the tire, such as a lubricant, an anti-aging agent, an accelerator, white carbon black (silicon dioxide), zinc sulfide, calcium carbonate, pottery clay and the like, so that the ash content in the cracking carbon black is higher, the general ash content is 11-19%, and the ash content is far higher than the specification of 0.7% of the national standard (GB3778-2011) of commercial carbon black for rubber. The existence of the ash not only covers the active sites of the carbon black, but also seriously influences the structural strength of the carbon black, and greatly reduces the reinforcing performance of the carbon black. Therefore, it is necessary to develop a high-efficiency, simple and environment-friendly purification method of cracking carbon black, reduce the petroleum consumption of commercial carbon black prepared by low-temperature combustion of crude oil, and improve the reinforcing performance of regenerated carbon black.
At present, the purification method of the cracking carbon black mainly comprises a physical method and a chemical method. Physical methods generally adopt methods such as gravity separation, air separation or flotation to separate carbon black impurities. Typical examples such as patent application CN201810947728.3, where physical deashing is performed, are relatively complicated processes and the reduction of ash is not significant. Patent application CN201911291634.6 reports that the oil content in carbon black is reduced by physical steps of drying, cooling, magnetic separation, milling etc., but the ash content variation is not illustrated. Relatively speaking, the chemical method has more remarkable impurity removal effect. The existing method mainly comprises two types, namely acid washing and acid-alkali combined washing, and the waste acid and the waste alkali generated in the acid washing process are easy to generate secondary pollution and discharge problems. For example, patent application CN201110293482.0 reports that the purification of carbon black by using dilute nitric acid-alkali combined washing to remove zinc oxide, calcium carbonate and sulfide from carbon black reduces its ash content from 18.7% to 2.6%, which is still far from 0.7% ash standard of commercial carbon black, and the main reason may be that part of silica in the ash content is not completely dissolved and removed in dilute alkali solution; the patent application CN202010154056.8 adopts a method of organic weak acid complexation and acid solution dissolution leaching to purify carbon black, but does not relate to the recycling of waste acid; the subject group of Qingdao science and technology university respectively adopts hydrochloric acid, sulfuric acid and nitric acid to treat the cracked carbon black, the ash content is respectively reduced from 14.226% to 6.342%, 9.264% and 6.102%, and the ash content is still obviously higher than the national commercial carbon black standard; the subject group of Taiyuan university respectively adopts hydrochloric acid/hydrofluoric acid and hydrochloric acid/sodium hydroxide to purify the cracked carbon black under the assistance of ultrasonic waves, the ash content of the cracked carbon black can be reduced from 13.98% to 0.24% through the hydrochloric acid/hydrofluoric acid and the hydrochloric acid/sodium hydroxide, the ash removal effect is obvious, the ash content of the cracked carbon black is reduced from 13.98% to 0.91% and is close to the standard of commercial carbon black, but the hydrofluoric acid in the raw materials has great harm to people, and the whole experimental design does not relate to post-treatment of waste acid liquid and recycling of resources.
Therefore, it is necessary to develop a method for effectively reducing the ash content in the cracked carbon black and effectively recycling resources.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a method for purifying cracked carbon black and producing a byproduct of fluosilicic acid, which can reduce the ash content in the cracked carbon black and produce the byproduct of fluosilicic acid at the same time, thereby fully realizing the effective utilization of resources.
In order to achieve the above object, the present invention provides a method for purifying cracked carbon black and by-producing fluosilicic acid, comprising the steps of:
(1) carrying out first contact on the cracking carbon black and an acid solution, and then carrying out solid-liquid separation to obtain a first filtrate and first carbon black containing a silicon compound;
(2) carrying out second contact on the first carbon black containing the silicon compound and a solution containing fluosilicic acid, and then carrying out solid-liquid separation to obtain second carbon black and a second filtrate;
(3) and purifying the second filtrate to obtain the fluosilicic acid.
Preferably, the acid of step (1) comprises a first acid and a second acid, the first acid is hydrochloric acid and/or nitric acid, and the second acid is at least one of acetic acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid and fluorosilicic acid.
Preferably, the solution containing fluosilicic acid also contains hydrofluoric acid, and further preferably, at least part of the solution containing fluosilicic acid is provided by a fluorine-containing waste acid solution obtained in the production process of phosphate fertilizer.
Compared with the prior art, the invention has the advantages that:
(1) according to the invention, two-step acid washing steps are adopted, and metal elements and silicon elements in the cracking carbon black are respectively subjected to targeted separation, so that the cracking carbon black with higher purity is obtained, the additional value of the cracking carbon black is greatly improved, and positive effects on improving the problems of waste tire resource waste, environmental pollution and the like in China are achieved;
(2) the method has the advantages of simple process, economy, environmental protection, easy realization of large-scale production and better development prospect.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a method for purifying cracked carbon black and by-producing fluosilicic acid, which comprises the following steps:
(1) carrying out first contact on the cracking carbon black and an acid solution, and then carrying out solid-liquid separation to obtain a first filtrate and first carbon black containing a silicon compound;
(2) carrying out second contact on the first carbon black containing the silicon compound and a solution containing fluosilicic acid, and then carrying out solid-liquid separation to obtain second carbon black and a second filtrate;
(3) and purifying the second filtrate to obtain the fluosilicic acid.
According to the present invention, preferably, the acid of step (1) is selected from at least one of hydrochloric acid, formic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid, fluorosilicic acid, ethylsulfonic acid and perchloric acid.
According to a preferred embodiment of the present invention, the acid of step (1) includes a first acid and a second acid, the first acid is hydrochloric acid and/or nitric acid, and the second acid is at least one of acetic acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid and fluorosilicic acid. During the research process, the inventor of the present invention found that the first acid and the second acid in the above preferred embodiment are adopted to cooperate to be more beneficial to leaching of metal ions.
Preferably, the molar ratio of the first acid to the second acid is from 2 to 100: 1, more preferably 9 to 50: 1.
according to the present invention, preferably, the concentration of the acid solution of the step (1) is 0.1 to 15 mol. L-1More preferably 0.5 to 6 mol. L-1. When the acid includes a first acid and a second acid, the concentration of the acid solution refers to the total concentration of the two. In the invention, the solute of the acid solution is acid, and the concentration of the acid solution refers to the molar concentration of the acid.
According to the present invention, preferably, the amount of the acid solution used in step (1) is 5 to 20mL, more preferably 10 to 15mL, relative to 1g of the cracked carbon black.
The conditions for the first contact in step (1) of the present invention are selected from a wide range as long as the cracked carbon black and the acid solution are sufficiently reacted, and preferably, the conditions for the first contact in step (1) include: the temperature is 20-80 deg.C, and the time is 10-600 min; preferably, the temperature is 40-60 deg.C and the time is 60-300 min.
In order to make the reaction of the cracked carbon black and the acid solution more uniform, preferably, the first contacting in step (1) is carried out under stirring conditions, and further preferably, the stirring speed is 50-1000rpm, preferably 200-800 rpm.
The reaction of the first contact in the step (1) mainly comprises the following steps:
2H++ZnS→Zn2++H2S↑ (1)
2H++ZnO→Zn2++H2O (2)
2H++CaCO3→Ca2++CO2↑+H2O (3)
because the sulfur content in the cracking carbon black is high, the waste gas generated in the step (1) is mainly hydrogen sulfide, and therefore, alkali liquor or soda lime can be adopted to effectively recover hydrogen sulfide gas.
Preferably, the method further comprises: and (2) recovering hydrogen sulfide waste gas generated by the first contact in the step (1) by adopting alkali liquor and/or soda lime. Preferably, the main component of the alkali liquor is sodium hydroxide and/or potassium hydroxide. Reactions in which such recovery occurs primarily include, but are not limited to:
H2S+2NaOH→Na2S+2H2O (4)
H2S+2KOH→K2S+2H2O (5)
H2S+CaO→CaS+H2O (6)
the present invention is not particularly limited with respect to the specific operation and conditions of the recovery. The person skilled in the art knows how to carry out a specific recovery operation on the basis of the above disclosure.
Because the polarity of the two components of the cracked carbon black and the acid solution is greatly different, in order to further promote the sufficient contact of the two components, a carbon black surfactant is preferably introduced into the first contact. According to the present invention, preferably, a carbon black surfactant is further introduced into the first contact in the step (1).
The present invention has a wide range of selection of the carbon black surfactant as long as the cracked carbon black can be sufficiently contacted with the acid solution, and preferably, the carbon black surfactant is at least one selected from the group consisting of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, hydrogen peroxide and oxygen.
Preferably, the carbon black surfactant is at least one selected from the group consisting of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid and hydrogen peroxide, and is added in an amount of 0.5 to 6 parts by weight, preferably 1 to 4 parts by weight, relative to 100 parts by weight of the cleaved carbon black.
Preferably, the carbon black surfactant is oxygen, and the flow rate of the oxygen is 10 to 1000mL/min, preferably 30 to 500mL/min, relative to 100g of the cracked carbon black.
According to the invention, the first filtrate can be recycled as the next pickling mother liquor after being recovered.
According to the present invention, preferably, the method further comprises: the first carbon black containing the silicon compound is washed and then optionally dried. The detergent can be deionized water, and the washing times can be 2-3 times. Preferably, the drying conditions include: the drying temperature is 80-180 deg.C, and the drying time is 1-24 hr, preferably 2-14 hr.
In the present invention, the silicon compound is a compound containing elemental silicon, and may be, for example, silicon dioxide, silicate, or other forms containing silicon, which is not limited in any way in the present invention.
According to the present invention, preferably, the concentration of the solution containing fluorosilicic acid is from 0.5 to 60% by weight, preferably from 5 to 35% by weight.
According to the present invention, it is preferred that the amount of the solution containing fluorosilicic acid in step (2) is 5 to 20mL, more preferably 10 to 15mL, relative to 1g of the first carbon black containing a silicon compound.
According to the present invention, preferably, the conditions of the second contacting of step (2) include: the temperature is 20-80 deg.C, and the time is 10-600 min; further preferably, the temperature is 50-60 ℃ and the time is 60-480 min.
According to the present invention, preferably, the second contacting in step (2) is performed under stirring conditions, further preferably, the stirring speed is 50-1000rpm, preferably 300-800 rpm.
The above-described conditions of the preferred second contact are more favorable for the first carbon black containing the silicon compound to react sufficiently with the solution containing fluorosilicic acid.
According to a preferred embodiment of the present invention, the solution containing fluorosilicic acid also contains hydrofluoric acid, which reacts with the silicon-containing compound to form fluorosilicic acid. The adoption of the preferred embodiment is more beneficial to obviously reducing ash content and simultaneously is more beneficial to improving the concentration of the fluosilicic acid and the silicon removal efficiency. In this preferred embodiment, the second contact in step (2) mainly comprises the following reactions:
SiO2+6HF→H2SiF6+2H2O (8)
SiO2+2H2SiF6→2SiF4+2H2O (9)
according to the present invention, it is preferable that the solution containing fluorosilicic acid has a fluorosilicic acid content of 15 to 50% by weight and a hydrofluoric acid content of 1 to 20% by weight; further preferably, the content of the fluosilicic acid is 20 to 35 wt%, and the content of the hydrofluoric acid is 2 to 15 wt%.
In the present invention, the source of the fluorosilicic acid-containing solution is not particularly limited, but in order to further reduce the cost, it is preferable from the viewpoint of resource recycling that at least part of the fluorosilicic acid-containing solution is supplied from a fluorine-containing waste acid solution obtained in a phosphate fertilizer production process. Fluorine-containing waste obtained in phosphate fertilizer production process
The acid solution contains fluosilicic acid and hydrofluoric acid, and the inventor of the invention finds in the research process that the application of the acid solution as the fluosilicic acid-containing solution in the step (2) is particularly beneficial to recycling of waste resources.
In the production of phosphate fertilizer, common calcium is a main product, and the preparation reaction is as follows:
2Ca5(PO4)3F+7H2SO4+3H2O→3Ca(H2PO4)2·H2O+7CaSO4+2HF↑ (7)。
after mixing and forming, the mixture is escaped with SiF4Absorbing the main fluorine-containing mixed gas with water to obtain the fluorine-containing waste acid solution.
It can be understood that when the content of fluosilicic acid and hydrofluoric acid in the fluorine-containing waste acid solution obtained in the phosphate fertilizer production process cannot meet the above preferable requirements, the treatment can be performed by adopting the modes of dilution, concentration, fluosilicic acid addition or hydrofluoric acid addition.
According to the present invention, preferably, the method further comprises: the second carbon black is washed and then optionally dried. The detergent can be deionized water, and the washing times can be 3-5 times. Preferably, the drying conditions include: the drying temperature is 80-120 ℃, and the drying time is 12-24 h.
According to the invention, the purification of step (3) comprises: mixing the second filtrate with lead fluorosilicate and calcium fluorosilicate to remove sulfate ions and fluoride ions from the second filtrate. The specific manner of mixing the second filtrate with the lead fluorosilicate and the calcium fluorosilicate is not particularly limited, and the second filtrate may be simultaneously mixed with the lead fluorosilicate and the calcium fluorosilicate, or mixed with one of the lead fluorosilicate and the calcium fluorosilicate, and then the other substance is added.
The amount of the lead fluorosilicate and the calcium fluorosilicate added is not particularly limited, and is based on the fact that sulfate ions and fluoride ions in the second filtrate can be removed. For example, the lead fluorosilicate may be added in an amount of 5 to 10 wt% of the second filtrate; the amount of calcium fluorosilicate added may be from 2 to 8 wt% of the second filtrate.
The conditions for mixing the second filtrate with the lead fluorosilicate and the calcium fluorosilicate are not particularly limited in the present invention, and the reaction temperature may be controlled to 25 to 60 ℃.
The specific reaction in the step (3) mainly comprises:
the source of the pyrolysis carbon black is not particularly limited in the present invention, and preferably, the pyrolysis carbon black is obtained by subjecting waste tires to pyrolysis treatment. Generally, the ash of said cracked carbon blackThe weight percentage is 11-19%. The cracking carbon black mainly contains SiO2、CaCO3ZnS, ZnO and pottery clay. SiO based on the total amount of the cracking carbon black2、CaCO3The weight percentages of ZnS, ZnO and pottery clay are (6-9.5): (1-2): (1-2): (1.5-3): (1.5-2.5).
According to the present invention, preferably, the method further comprises: before the step (1), the cracked carbon black is subjected to a pre-treatment for removing a colloidal layer. Further preferably, the colloid layer removing pretreatment comprises:
1) grinding the cracked carbon black;
2) and (3) carbonizing the cracked carbon black obtained by grinding at high temperature. Under the preferred scheme, the ash content is further reduced, and simultaneously the fluosilicic acid by-product is produced.
According to the invention, preferably, the grinding time is between 0.1 and 1.5 h.
According to the present invention, it is preferable that the particle size of the cracked carbon black obtained by grinding is 160-500 mesh.
Preferably, the high-temperature carbonization conditions include: under the inert atmosphere, the temperature is 600-800 ℃, and the time is 0.1-3 h. The inert atmosphere is provided by an inert gas including, but not limited to, at least one of helium, neon, argon, and nitrogen.
The present invention will be described in detail below by way of examples. In the following examples, the cracked carbon black, which had an ash content of 18.6% by weight, was obtained by subjecting used tires to pyrolysis treatment. The ash parameter of the cracked carbon black is measured by a GB/T3780.10-2017 method; the raw materials are primary products of Zhongshi rubber company.
Example 1
(1) Placing 0.35 kg of pyrolysis carbon black and 3.5L of hydrochloric acid solution (5 mol. L-1) in a 5L reaction kettle, controlling the reaction temperature at 60 ℃, stirring for 3h and stirring at 500 rpm; after the reaction is finished, filtering and separating to obtain a first filtrate and first carbon black containing the silicon compound (which can be recycled for next pickling solution).
(2) Adding the first carbon black obtained in the step (1) and a solution containing fluosilicic acid (containing 25 wt% of fluosilicic acid and 3 wt% of hydrofluoric acid, wherein the solution containing fluosilicic acid is obtained by mixing and diluting a fluorine-containing waste acid solution obtained in a phosphate fertilizer production process with deionized water, wherein the weight ratio of the fluorine-containing waste acid solution to the deionized water is 1:1) into a second reaction kettle, controlling the reaction temperature to be 60 ℃, stirring for 6 hours and stirring at the speed of 600 rpm; after the reaction is finished, obtaining a carbon black filter cake and a second filtrate through filtering and separation. Washing the carbon black filter cake with deionized water for 4 times until the carbon black filter cake is neutral, and then drying the carbon black filter cake for 24 hours at 120 ℃ to obtain a carbon black product.
(3) And adding lead fluosilicate and calcium fluosilicate into the second filtrate, wherein the adding amount is 10 percent and 5 percent of the weight of the second filtrate respectively, stirring for 1 hour at the temperature of 30 ℃, and filtering to obtain a fluosilicic acid byproduct.
Examples 2 to 5
The procedure of example 1 was followed except that the specific conditions of each step are shown in Table 1 below.
TABLE 1
Note: the dosage of the acid solution in the step (1) and the dosage of the acid solution in the step (3) are respectively the dosage of 1g of the cracked carbon black and the carbon black after acid washing in the step (1); the contents of fluorosilicic acid and hydrofluoric acid refer to the contents in a solution containing fluorosilicic acid.
Example 6
The procedure is as in example 1, except that 5 mol. L in step (1)-1The 3.5L of hydrochloric acid solution is replaced by 3.5L of mixed solution containing the first acid (hydrochloric acid) and the second acid (acetic acid), and the concentrations of the two components are respectively 4.9 mol.L-1And 0.1 mol. L-1。
Example 7
The procedure is as in example 1, except that 5 mol. L in step (1)-13.5L hydrochloric acid solutionThe solution is replaced by 3.5L of mixed solution containing a first acid (hydrochloric acid) and a second acid (acetic acid), and the concentrations of the two components are respectively 4.5 mol.L-1And 0.5 mol. L-1
Example 8
The process of example 1 was followed except that step (1) further included introducing oxygen into the reactor at a flow rate of 400mL/min relative to 100g of the cracked carbon black.
Example 9
The method according to example 1 except that step (1) further comprises introducing into said reaction tank a carbon black surfactant, monofluoroacetic acid (i.e., monofluoroacetic acid and said cleaved carbon black are co-introduced into said three-neck flask), said carbon black surfactant being added in an amount of 3 parts by weight relative to 100 parts by weight of said cleaved carbon black.
Example 10
The method according to embodiment 1, except that the method further comprises: before the step (1), the cracking carbon black is subjected to a colloid layer removal pretreatment, wherein the colloid layer removal pretreatment comprises the following steps:
1) grinding the cracking carbon black for 1h to ensure that the particle size of the cracking carbon black is 230-500 meshes;
2) carrying out high-temperature carbonization on the cracked carbon black obtained by grinding; the high-temperature carbonization conditions comprise: the reaction is carried out under the nitrogen atmosphere, the temperature is 700 ℃, and the time is 2 h.
Example 11
(1) 0.35 kg of the cracked carbon black was placed in a 5L reactor, the reaction temperature was controlled at 25 ℃ and then 1.5L of a hydrochloric acid solution (0.05 mol. L) was added-1) The stirring time is 3h, and the stirring speed is 500 rpm; and after the reaction is finished, filtering and separating to obtain a first filtrate and first carbon black containing a silicon compound.
(2) Adding the first carbon black obtained in the step (1) and a solution containing fluosilicic acid (containing 10 wt% of fluosilicic acid and 0.5 wt% of hydrofluoric acid), wherein the solution containing fluosilicic acid is obtained by mixing and diluting a fluorine-containing waste acid solution obtained in a phosphate fertilizer production process with deionized water, the weight ratio of the fluorine-containing waste acid solution to the deionized water is 1:1) into a second reaction kettle, controlling the reaction temperature to be 25 ℃ relative to 1g of the first carbon black obtained in the step (1), and then starting stirring for 6 hours at the stirring speed of 600 rpm; after the reaction is finished, obtaining a carbon black filter cake and a second filtrate through filtering and separation. Washing the carbon black filter cake with deionized water for 4 times until the carbon black filter cake is neutral, and then drying the carbon black filter cake for 24 hours at 120 ℃ to obtain a carbon black product.
(3) Adding lead fluosilicate and calcium fluosilicate into the second filtrate, wherein the adding amount is respectively 10 percent and 5 percent of the weight of the second filtrate, stirring for 1 hour at the temperature of 30 ℃, and filtering to obtain a fluosilicic acid byproduct.
The carbon black products and the fluorosilicic acid by-products obtained in examples 1 to 11 were analyzed for their contents, and the results of the ash content in the carbon black products and the fluorosilicic acid content in the fluorosilicic acid by-products are shown in Table 2 below.
TABLE 2
| Ash content (% by weight) | Content of Fluorosilicic acid (wt%) | |
| Example 1 | 0.51 | 32.63 |
| Example 2 | 0.53 | 39.64 |
| Example 3 | 0.62 | 28.13 |
| Example 4 | 0.78 | 32.59 |
| Example 5 | 0.84 | 39.61 |
| Example 6 | 0.45 | 32.63 |
| Example 7 | 0.42 | 32.64 |
| Example 8 | 0.49 | 32.62 |
| Example 9 | 0.50 | 32.63 |
| Example 10 | 0.32 | 32.65 |
| Example 11 | 11.75 | 30.72 |
As can be seen from the results in Table 2, the method of the present invention can reduce the ash content in the cracked carbon black and produce the fluosilicic acid by-product, thereby fully realizing the effective utilization of resources. Further, in the preferred embodiment of the present invention, the ash content was 0.45% and 0.42% respectively with the aid of the composite acid (example 6 and example 7), which is significantly superior to the effect of example 1. In addition, it can be seen from example 9 that the addition of a carbon black surfactant to the waste acid promotes the improvement of the purity of the carbon black. Comparing example 1 and example 10, it can be seen that the preferred embodiment of the present invention, which includes a pretreatment step, is more advantageous in further reducing the ash content while producing the fluosilicic acid by-product. Comparing example 1 and example 11, it can be seen that the use of the preferred specific process parameters of the present invention (e.g., amount of acid and corresponding contact temperature) is more advantageous for significantly reducing ash content while producing fluorosilicic acid by-product.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A method for purifying cracked carbon black and by-producing fluosilicic acid is characterized by comprising the following steps:
(1) carrying out first contact on the cracking carbon black and an acid solution, and then carrying out solid-liquid separation to obtain a first filtrate and first carbon black containing a silicon compound;
(2) carrying out second contact on the first carbon black containing the silicon compound and a solution containing fluosilicic acid, and then carrying out solid-liquid separation to obtain second carbon black and a second filtrate;
(3) and purifying the second filtrate to obtain the fluosilicic acid.
2. The method according to claim 1, wherein the acid of step (1) is selected from at least one of hydrochloric acid, formic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid, fluorosilicic acid, ethylsulfonic acid, and perchloric acid;
preferably, the acid of step (1) comprises a first acid and a second acid, the first acid is hydrochloric acid and/or nitric acid, and the second acid is at least one of acetic acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid and fluorosilicic acid;
preferably, the molar ratio of the first acid to the second acid is from 2 to 100: 1, more preferably 9 to 50: 1;
preferably, the concentration of the acid solution in the step (1) is 0.1-15 mol.L-1More preferably 0.5 to 6 mol. L-1；
Preferably, the amount of the acid solution used in step (1) is 5 to 20mL, more preferably 10 to 15mL, relative to 1g of the cracked carbon black.
3. The method of claim 1 or 2, wherein the conditions of the first contacting of step (1) comprise: the temperature is 20-80 deg.C, and the time is 10-600 min; preferably, the temperature is 40-60 ℃, and the time is 60-300 min;
preferably, the first contacting in step (1) is carried out under stirring conditions, further preferably, the stirring speed is 50-1000rpm, preferably 200-800 rpm;
preferably, the method further comprises: and (2) recovering hydrogen sulfide waste gas generated by the first contact in the step (1) by adopting alkali liquor and/or soda lime.
4. The method of any one of claims 1-3, wherein a carbon black surfactant is further introduced into the first contacting of step (1);
preferably, the carbon black surfactant is selected from at least one of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, hydrogen peroxide and oxygen;
preferably, the carbon black surfactant is at least one selected from the group consisting of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid and hydrogen peroxide, and is added in an amount of 0.5 to 6 parts by weight, preferably 1 to 4 parts by weight, relative to 100 parts by weight of the cleaved carbon black;
preferably, the carbon black surfactant is oxygen, and the flow rate of the oxygen is 10 to 1000mL/min, preferably 30 to 500mL/min, relative to 100g of the cracked carbon black.
5. A process according to any one of claims 1 to 4, characterized in that the concentration of the solution containing fluorosilicic acid is from 0.5 to 60 weight percent, preferably from 5 to 35 weight percent;
preferably, the amount of the solution containing fluorosilicic acid of step (2) is 5 to 20mL, more preferably 10 to 15mL, relative to 1g of the first carbon black containing a silicon compound;
preferably, the conditions of the second contacting of step (2) include: the temperature is 20-80 deg.C, and the time is 10-600 min; further preferably, the temperature is 50-60 ℃, and the time is 60-480 min;
preferably, the second contacting in step (2) is performed under stirring conditions, further preferably, the stirring speed is 50-1000rpm, preferably 300-800 rpm.
6. A process according to any one of claims 1 to 5 wherein the solution containing fluorosilicic acid also contains hydrofluoric acid;
preferably, in the solution containing fluosilicic acid, the content of the fluosilicic acid is 15-50 wt%, and the content of hydrofluoric acid is 1-20 wt%; further preferably, the content of the fluosilicic acid is 20-35 wt%, and the content of the hydrofluoric acid is 2-15 wt%;
further preferably, at least part of the solution containing fluosilicic acid is provided by fluorine-containing waste acid solution obtained in the production process of phosphate fertilizer.
7. The method according to any one of claims 1 to 6, wherein the purification of step (3) comprises: and mixing the second filtrate with lead fluosilicate and calcium fluosilicate to remove sulfate ions and fluoride ions in the second filtrate.
8. The process according to any one of claims 1 to 7, characterized in that the said cracked carbon black is obtained by pyrolysis of used tires.
9. The method of any one of claims 1 to 8, optionally further comprising: before the step (1), the cracked carbon black is subjected to a pre-treatment for removing a colloidal layer.
10. The method of claim 9, wherein the desmear pretreatment comprises:
1) grinding the cracked carbon black;
2) carrying out high-temperature carbonization on the cracked carbon black obtained by grinding;
preferably, the grinding time is 0.1-1.5 h;
preferably, the particle size of the cracked carbon black obtained by grinding is 160-500 meshes;
preferably, the high-temperature carbonization conditions include: under the inert atmosphere, the temperature is 600-800 ℃, and the time is 0.1-3 h.
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