CN114436236A - Method for purifying and by-producing fluorosilicic acid by cracking carbon black - Google Patents

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

Method for purifying and by-producing fluorosilicic acid by cracking carbon black

technical field

The invention relates to the technical field of solid waste resource utilization, in particular to a method for purifying pyrolysis carbon black and by-producing fluorosilicic acid.

Background technique

With the rapid development of my country's social economy, it has greatly promoted the rapid growth and popularization of people's automobile consumption. According to statistics, in the first half of 2019, the number of motor vehicles has reached 340 million, of which 26.52 million were newly registered civilian vehicles in my country in 2018. As the only consumable part of the car in contact with the ground, the production and consumption of tires are closely related to the automobile industry. Among the top 75 tire companies in the world, a number of national industries such as Chaoyang, Linglong and Triangle have emerged in my country, accounting for 45% of the seats, making China a veritable tire country. Usually the life of a car tire is 5-8 years or 60,000-80,000 miles. These scrapped tires contain a lot of rubber, steel wire, silica and carbon black, as well as organic accelerators, zinc sulfide, alumina, calcium carbonate and additives such as clay. The annual output of waste tires in my country reaches more than 13 million tons, and it is still growing at an annual rate of 8%-10%. With the increasing amount of scrap tires scrapped, the processing pressure is increasing. At present, there are four main treatment methods for waste tires, namely refurbishment, regeneration, incineration and pyrolysis. The first two methods are affected by the state of the tire itself during the disposal process, resulting in unstable quality of retreaded tires or reclaimed rubber powder. In the case of the third type, it is easy to produce toxic exhaust gas during the incineration process, which leads to secondary pollution and fails to fundamentally solve the pollution problem of waste tires. Correspondingly, the fourth pyrolysis method is a method of heat-treating organic components in tires under anoxic conditions.

The pyrolysis process of tires refers to cutting waste tires into small pieces of 3-5cm, and then putting them into a sealed tunnel kiln for heat treatment at 400-460 ° C for half an hour, so that the waste tire blocks are converted into pyrolysis gas, heat It consists of four parts: oil solution, pyrolysis carbon (also known as cracked carbon black) and steel wire. The pyrolysis gas obtained by pyrolysis is usually directly returned to the furnace as the fuel required for 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 being separated by magnetic separation. Pyrolysis carbon black mainly contains various grades of reinforcing carbon black, filler carbon black and other carbon black produced by the decomposition of organic matter during pyrolysis, as well as various additives added in tires, such as lubricants, antioxidants, accelerators, Silica (silicon dioxide), zinc sulfide, calcium carbonate and clay, etc., lead to high ash content in cracked carbon black, generally 11%-19%, much higher than the national standard for commercial carbon black for rubber (GB3778 -2011) 0.7% regulation. The existence of these ash not only covers the active sites of carbon black, but also seriously affects the structural strength of carbon black and greatly reduces its reinforcing properties. Therefore, it is particularly necessary to develop an efficient, simple and environmentally friendly method for purifying pyrolysis carbon black, to reduce the oil consumption of commercial carbon black prepared by low-temperature combustion of crude oil, and to improve the reinforcing properties of regenerated carbon black.

At present, the purification methods of cracked carbon black mainly include physical method and chemical method. The physical method usually adopts methods such as gravity separation, air separation or flotation to separate carbon black impurities. A typical example such as patent application CN201810947728.3 adopts physical method to deash, the process is relatively complicated, and the reduction of ash content is not obvious. Patent application CN201911291634.6 reported that the oil content in carbon black was reduced by physical steps such as drying, cooling, magnetic separation, and milling, but the change in ash content was not explained. Relatively speaking, the chemical method has a more significant impurity removal effect. Existing methods are mainly divided into two types, pickling and acid-alkali combined washing. The waste acid and waste alkali generated in the pickling process are prone to secondary pollution and discharge problems. For example, patent application CN201110293482.0 reported the method of removing zinc oxide, calcium carbonate and sulfide in carbon black by using dilute nitric acid-alkali combined washing to purify carbon black and reduce its ash content from 18.7% to 2.6%, which is less than commercial carbon black. The 0.7% ash standard is still far away, and the main reason may be that part of the silica in the ash is not completely dissolved and removed in the dilute alkali solution; the patent application CN202010154056.8 adopts the method of organic weak acid complexation and acid solution dissolution and leaching to purify carbon black, However, the recycling of waste acid is not involved; the research group of Qingdao University of Science and Technology used hydrochloric acid, sulfuric acid and nitric acid to treat the cracked carbon black respectively, and the ash content was reduced from 14.226% to 6.342%, 9.264% and 6.102%, which were still significantly higher than National commercial carbon black standard; the research group of Taiyuan University of Technology used hydrochloric acid/hydrofluoric acid and hydrochloric acid/sodium hydroxide to purify cracked carbon black with the aid of ultrasonic waves, the former can reduce the ash content of cracked carbon black from 13.98% to 0.24% , the ash removal effect is remarkable, the ash content of the latter is reduced from 13.98% to 0.91%, which is close to the standard of commercial carbon black, but the hydrofluoric acid in the raw material is more harmful to human beings, and the whole experimental design does not involve the post-treatment and treatment of waste acid solution. Recycling and recycling of resources.

Therefore, there is an urgent need to develop a method that effectively reduces the ash content in pyrolysis carbon black and can realize effective resource recycling.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, and provide a method for purifying pyrolysis carbon black and by-producing fluorosilicic acid, which can produce fluorosilicic acid by-product while reducing the ash content in the pyrolysis carbon black. , to fully realize the effective use of resources.

In order to achieve the above object, the present invention provides a method for purifying and by-producing fluorosilicic acid by cracking carbon black, the method comprising the following steps:

(1) cracking carbon black and acid solution are carried out first contact, then carry out solid-liquid separation to obtain the first filtrate and the first carbon black containing silicon compound;

(2) carrying out the second contact with the first carbon black containing the silicon compound and the solution containing fluorosilicic acid, and then carrying out solid-liquid separation to obtain the second carbon black and the second filtrate;

(3) purifying the second filtrate to obtain fluorosilicic acid.

Preferably, the acid in 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 acetic acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid At least one of acid and fluorosilicic acid.

Preferably, the fluorosilicic acid-containing solution further contains hydrofluoric acid, and further preferably, at least part of the fluorosilicic acid-containing solution is provided from a fluorine-containing waste acid solution obtained during the production of phosphate fertilizer.

Compared with the prior art, the advantages of the present invention are:

(1) The present invention adopts two-step pickling steps to separate metal elements and silicon elements in the cracked carbon black in a targeted manner to obtain a relatively high-purity cracked carbon black, which greatly improves its added value, and is useful for improving my country's waste The waste of tire resources and the resulting environmental pollution have played a positive role;

(2) The process of the invention is simple, economical and environmentally friendly, easy to realize large-scale production, and has a good development prospect.

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

The invention provides a method for purifying and by-producing fluorosilicic acid by cracking carbon black, the method comprises the following steps:

(1) cracking carbon black and acid solution are carried out first contact, then carry out solid-liquid separation to obtain the first filtrate and the first carbon black containing silicon compound;

(2) carrying out the second contact with the first carbon black containing the silicon compound and the solution containing fluorosilicic acid, and then carrying out solid-liquid separation to obtain the second carbon black and the second filtrate;

(3) purifying the second filtrate to obtain fluorosilicic acid.

According to the present invention, preferably, the acid in step (1) is selected from hydrochloric acid, formic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid, fluorosilicic acid, ethylsulfonic acid and At least one of perchloric acid.

According to a preferred embodiment of the present invention, the acid in 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 acetic acid, hydrofluoric acid, At least one of methanesulfonic acid, sulfamic acid and fluorosilicic acid. The inventors of the present invention found in the research process that the use of the first acid and the second acid in the above preferred embodiment is more favorable for the leaching of metal ions.

Preferably, the molar ratio of the first acid and the second acid is 2-100:1, more preferably 9-50:1.

According to the present invention, preferably, the concentration of the acid solution in step (1) is 0.1-15 mol·L ^-1 , more preferably 0.5-6 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 both. In the present 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, relative to 1 g of the pyrolysis carbon black, the amount of the acid solution in step (1) is 5-20 mL, more preferably 10-15 mL.

The present invention has a wide range of conditions for the first contact in step (1), as long as the pyrolysis carbon black and the acid solution are fully reacted. Preferably, the conditions for the first contact in step (1) include: a temperature of 20-80°C, time is 10-600min; preferably, temperature is 40-60°C, time is 60-300min.

In order to make the reaction between the cracked carbon black and the acid solution more uniform, preferably, the first contact in step (1) is carried out under stirring conditions, further preferably, the stirring speed is 50-1000 rpm, preferably 200-800 rpm.

The reaction that the described first contact of step (1) occurs mainly includes:

2H ⁺ +ZnS→Zn ²⁺ +H ₂ S↑ (1)

2H ⁺ +ZnO→Zn ²⁺ +H ₂ O (2)

2H ⁺ +CaCO ₃ →Ca ²⁺ +CO ₂ ↑+H ₂ O (3)

Since the sulfur content in the cracked carbon black is relatively high, the waste gas produced in step (1) is mainly hydrogen sulfide, so lye or soda lime can be used to effectively recover the hydrogen sulfide gas.

Preferably, the method further comprises: recovering the hydrogen sulfide waste gas produced by the first contact in step (1) using lye and/or soda lime. Preferably, the main components of the lye are sodium hydroxide and/or potassium hydroxide. The reaction that the recovery mainly occurs includes but is not limited to:

H ₂ S+2NaOH→Na ₂ S+2H ₂ O (4)

H ₂ S+2KOH→K ₂ S+2H ₂ O (5)

H ₂ S+CaO→CaS+H ₂ O (6)

The present invention does not specifically limit the specific operation and conditions of the recovery. Those skilled in the art will know how to perform specific recovery operations on the basis of the above disclosure.

Since the polarities of the two components, the cracked carbon black and the acid solution, are quite different, in order to further promote the full contact of the two components, it is preferable that a carbon black surfactant is also introduced into the first contact. According to the present invention, preferably, carbon black surfactant is also introduced into the first contact in step (1).

The present invention has a wide selection range for the types of the carbon black surfactant, as long as the cracked carbon black and the acid solution can be fully contacted, preferably, the carbon black surfactant is selected from monofluoroacetic acid, difluoroacetic acid , at least one of trifluoroacetic acid, hydrogen peroxide and oxygen.

Preferably, the carbon black surfactant is selected from at least one of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid and hydrogen peroxide, and relative to 100 parts by weight of the cracked carbon black, the carbon black surface The addition amount of the activator is 0.5-6 parts by weight, preferably 1-4 parts by weight.

Preferably, the carbon black surfactant is oxygen, and relative to 100 g of the pyrolysis carbon black, the oxygen flow rate is 10-1000 mL/min, preferably 30-500 mL/min.

According to the present invention, the first filtrate can be recycled as the next pickling mother liquor after recovery.

According to the present invention, preferably, the method further comprises: washing the first carbon black containing the silicon compound, and then optionally drying. The washing agent can be deionized water, and the washing times can be 2-3 times. Preferably, the drying conditions include: a drying temperature of 80-180° C. and a drying time of 1-24 h, preferably 2-14 h.

In the present invention, the silicon compound is a compound containing silicon element, such as silicon dioxide, silicate or other forms containing silicon, which is not limited in the present invention.

According to the present invention, preferably, the concentration of the solution containing fluorosilicic acid is 0.5-60% by weight, preferably 5-35% by weight.

According to the present invention, preferably, relative to 1 g of the first carbon black containing a silicon compound, the amount of the solution containing fluorosilicic acid in step (2) is 5-20 mL, more preferably 10-15 mL.

According to the present invention, preferably, the conditions of the second contact in step (2) include: the temperature is 20-80° C. and the time is 10-600 min; further preferably, the temperature is 50-60° C. and the time is 60-480 min.

According to the present invention, preferably, the second contact in step (2) is carried out under stirring conditions, further preferably, the stirring speed is 50-1000 rpm, preferably 300-800 rpm.

The above-mentioned preferably second contacting conditions are more favorable for the sufficient reaction of the first carbon black containing the silicon compound and the solution containing fluorosilicic acid.

According to a preferred embodiment of the present invention, the solution containing fluorosilicic acid further contains hydrofluoric acid, and the hydrofluoric acid reacts with the silicon-containing compound to generate fluorosilicic acid. Adopting this preferred embodiment is more conducive to significantly reducing the ash content, and at the same time, it is more conducive to improving the concentration of fluosilicic acid and the efficiency of silicon removal. Under this preferred scheme, the reaction that the second contact described in step (2) occurs mainly includes:

SiO ₂ +6HF→H ₂ SiF ₆ +2H ₂ O (8)

SiO ₂ +2H ₂ SiF ₆ →2SiF ₄ +2H ₂ O (9)

According to the present invention, preferably, in the solution containing fluorosilicic acid, the content of fluorosilicic acid is 15-50 wt %, and the content of hydrofluoric acid is 1-20 wt %; more preferably, the content of fluorosilicic acid is 20-35% by weight, and the content of hydrofluoric acid is 2-15% by weight.

The source of the solution containing fluorosilicic acid is not particularly limited in the present invention, but in order to further reduce costs, from the perspective of resource recycling, preferably, at least part of the solution containing fluorosilicic acid is obtained from the production process of phosphate fertilizer Fluorinated waste acid solution is provided. Fluorine-containing waste obtained during the production of phosphate fertilizers

The acid solution contains fluorosilicic acid and hydrofluoric acid, and the inventors of the present invention found in the research process that using it as a solution containing fluorosilicic acid in step (2) is particularly beneficial to the recycling of waste resources.

In the production of phosphate fertilizer, ordinary calcium is the main product, and its preparation reaction is:

2Ca ₅ (PO ₄ ) ₃ F+7H ₂ SO ₄ +3H ₂ O→3Ca(H ₂ PO ₄ ) ₂ ·H ₂ O+7CaSO ₄ +2HF↑ (7).

After being mixed and formed, the fluorine-containing mixed gas mainly composed of SiF ₄ escapes, and the fluorine-containing waste acid solution is obtained by absorbing it with water.

It can be understood that, when the content of fluorosilicic acid and hydrofluoric acid in the fluorine-containing waste acid solution obtained in the phosphate fertilizer production process cannot meet the above-mentioned preferred requirements, the methods of dilution, concentration, addition of fluorosilicic acid or addition of hydrofluoric acid can be adopted. to be processed.

According to the present invention, preferably, the method further comprises: washing the second carbon black and then optionally drying. The washing agent can be deionized water, and the washing times can be 3-5 times. Preferably, the drying conditions include: a drying temperature of 80-120° C. and a drying time of 12-24 h.

According to the present invention, the purification in step (3) includes: mixing the second filtrate with lead fluorosilicate and calcium fluorosilicate to remove sulfate ions and fluoride ions in the second filtrate. The present invention does not specifically limit the specific manner of mixing the second filtrate with lead fluorosilicate and calcium fluorosilicate, and the second filtrate may be mixed with lead fluorosilicate and calcium fluorosilicate It may be that the second filtrate is mixed with one of lead fluorosilicate and calcium fluorosilicate, and then the other is added.

The present invention has no particular limitation on the addition amount of the lead fluorosilicate and calcium fluorosilicate, as long as the sulfate ions and fluoride ions in the second filtrate can be removed. For example, the addition amount of lead fluorosilicate may be 5-10% by weight of the second filtrate; the addition amount of calcium fluorosilicate may be 2-8% by weight of the second filtrate.

In the present invention, the conditions for mixing the second filtrate with lead fluorosilicate and calcium fluorosilicate are not particularly limited, for example, the reaction temperature can be controlled at 25-60°C.

The concrete reaction that takes place in the above-mentioned steps (3) mainly comprises:

The source of the pyrolysis carbon black is not particularly limited in the present invention. Preferably, the pyrolysis carbon black is obtained by pyrolysis of waste tires. In general, the ash content of the pyrolysis carbon black is 11-19% by weight. The pyrolysis carbon black mainly contains SiO ₂ , CaCO ₃ , ZnS, ZnO, and clay. Based on the total amount of the cracked carbon black, the weight percentages of SiO ₂ , CaCO ₃ , ZnS, ZnO and 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 includes: before step (1), pre-processing the cracked carbon black to remove the colloid layer. Further preferably, the pretreatment of the decolloid layer includes:

1) grinding the pyrolysis carbon black;

2) The pyrolysis carbon black obtained by grinding is subjected to high temperature carbonization. Under this preferred solution, it is more favorable to further reduce the ash content and simultaneously produce fluorosilicic acid by-products.

According to the present invention, preferably, the grinding time is 0.1-1.5h.

According to the present invention, preferably, the particle size of the cracked carbon black obtained by grinding is 160-500 mesh.

Preferably, the conditions for the high-temperature carbonization include: in an inert atmosphere, the temperature is 600-800° C., 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 means of examples. In the following examples, pyrolysis carbon black is obtained by pyrolysis of waste tires, and the ash content of the pyrolysis carbon black is 18.6% by weight. The ash content parameters of pyrolysis carbon black are measured by the method of GB/T3780.10-2017; the raw material is the primary product of Zhongce Rubber Company.

Example 1

(1) 0.35 kg of cracked carbon black and 3.5 L of hydrochloric acid solution (5 mol L-1) were placed in a 5 L reactor, the control reaction temperature was 60 ° C, the stirring time was 3 h, and the stirring speed was 500 rpm; after the reaction was completed, Carry out filtration and separation to obtain the first filtrate and the first carbon black containing the silicon compound (which can be recycled for the next pickling solution).

(2) The first carbon black obtained in step (1) and the solution containing fluorosilicic acid (containing 25% by weight of fluorosilicic acid and 3% by weight of hydrofluoric acid, the solution containing fluorosilicic acid produced from phosphate fertilizer by The fluorine-containing waste acid solution obtained in the process is obtained by mixing and diluting with deionized water, wherein the weight ratio of the fluorine-containing waste acid solution and deionized water is 1:1). After the reaction is completed, the carbon black filter cake and the second filtrate are obtained by filtration and separation. The carbon black filter cake was washed 4 times with deionized water until neutral, and then dried at 120 °C for 24 h to obtain the carbon black product.

(3) adding lead fluorosilicate and calcium fluorosilicate to the second filtrate in an amount of 10% and 5% of the weight of the second filtrate, stirring at 30° C. for 1 hour and filtering to obtain a by-product of fluorosilicate.

Example 2-5

According to the method of Example 1, the difference is that the specific conditions of each step are listed in Table 1 below.

Table 1

Note: The consumption of acid solution in step (1) and step (3) is respectively relative to the consumption of 1 g of the cracked carbon black and the carbon black after acid washing in step (1); the content of fluorosilicic acid and hydrofluoric acid Refers to the content in the solution containing fluorosilicic acid.

Example 6

According to the method of Example 1, the difference is that the 5mol·L ^-1 3.5L hydrochloric acid solution in step (1) is replaced by 3.5L of the mixed solution containing the first acid (hydrochloric acid) and the second acid (acetic acid), and the two The concentrations of the components were 4.9 mol·L ^-1 and 0.1 mol·L ^-1 , respectively.

Example 7

According to the method of embodiment 1, the difference is that the 5mol·L ^-1 3.5L hydrochloric acid solution in step (1) is replaced by 3.5L of the mixed solution containing the first acid (hydrochloric acid) and the second acid (acetic acid), and the two The concentrations of the components were 4.5 mol·L ^-1 and 0.5 mol·L ^-1 , respectively

Example 8

According to the method of embodiment 1, the difference is that step (1) also includes feeding oxygen into the reaction kettle, and relative to 100 g of the cracked carbon black, the feeding flow of the oxygen is 400 mL/min.

Example 9

According to the method of embodiment 1, the difference is that step (1) also includes introducing carbon black surfactant monofluoroacetic acid into the reaction kettle (that is, monofluoroacetic acid and the cracked carbon black are jointly introduced into the three-necked flask ), relative to 100 parts by weight of the pyrolysis carbon black, the amount of the carbon black surfactant added is 3 parts by weight.

Example 10

According to the method of Embodiment 1, the difference is that the method further comprises: before performing step (1), the pyrolysis carbon black is subjected to a colloid-removing layer pretreatment, and the colloid-removing layer pretreatment includes:

1) grinding the cracked carbon black for 1h, so that the particle size of the cracked carbon black is 230-500 mesh;

2) High-temperature carbonization is performed on the cracked carbon black obtained by grinding; the conditions for the high-temperature carbonization include: carrying out in a nitrogen atmosphere, the temperature is 700° C., and the time is 2 hours.

Example 11

(1) 0.35 kg of cracked carbon black was placed in a 5L reactor, and the reaction temperature was controlled at 25°C, then 1.5L of hydrochloric acid solution (0.05mol·L ^-1 ) was added, and the stirring time was 3h, and the stirring speed was 500rpm; After that, filtration and separation are performed to obtain the first filtrate and the first carbon black containing the silicon compound.

(2) The first carbon black obtained in step (1) and a solution containing fluorosilicic acid (containing 10% by weight of fluorosilicic acid and 0.5% by weight of hydrofluoric acid, the solution containing fluorosilicic acid produced by phosphate fertilizer by The fluorine-containing waste acid solution obtained in the process is obtained by mixing and diluting with deionized water, wherein the weight ratio of the fluorine-containing waste acid solution and deionized water is 1:1) adding in the second reaction kettle, and obtaining with respect to the step (1) of 1g The amount of the first carbon black containing fluorosilicic acid was 12 mL, the reaction temperature was controlled to be 25 ° C, and then the stirring was started, the stirring time was 6 h, and the stirring speed was set to 600 rpm; Carbon black filter cake and second filtrate. The carbon black filter cake was washed 4 times with deionized water until neutral, and then dried at 120 °C for 24 h to obtain the carbon black product.

(3) adding lead fluorosilicate and calcium fluorosilicate to the second filtrate in an amount of 10% and 5% of the weight of the second filtrate respectively, stirring at 30° C. for 1 h and filtering to obtain a by-product of fluorosilicate.

The carbon black products and fluorosilicic acid by-products obtained in the above examples 1-11 were analyzed for content, and the results of the ash content in the carbon black products and the fluorosilicic acid content in the fluorosilicic acid by-products are listed in Table 2 below.

Table 2

Ash content (wt%) Fluorosilicic acid content (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

It can be seen from the results in Table 2 that the method of the present invention can reduce the ash content in the pyrolysis carbon black, and at the same time produce the by-product of fluorosilicic acid, and fully realize the effective utilization of resources. Further, under the preferred embodiment of the present invention, with the help of the composite acid (Example 6 and Example 7), the ash content is 0.45% and 0.42%, respectively, which is obviously better than the effect of Example 1. In addition, we can also see from Example 9 that adding carbon black surfactant to waste acid can promote the improvement of carbon black purity. Comparing Example 1 and Example 10, it can be seen that using the preferred solution of the present invention including the pretreatment step is more conducive to further reducing the ash content and simultaneously producing fluorosilicic acid by-products. Comparing Example 1 and Example 11, it can be seen that the preferred solution of the preferred specific process parameters (such as the amount of acid and the corresponding contact temperature) of the present invention is more conducive to significantly reducing the ash content and producing fluosilicic acid by-products.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. a kind of method of cracking carbon black purification and by-product fluorosilicic acid, is characterized in that, this method may further comprise the steps: (1) cracking carbon black and acid solution are carried out first contact, then carry out solid-liquid separation to obtain the first filtrate and the first carbon black containing silicon compound; (2) carrying out the second contact with the first carbon black containing the silicon compound and the solution containing fluorosilicic acid, and then carrying out solid-liquid separation to obtain the second carbon black and the second filtrate; (3) purifying the second filtrate to obtain fluorosilicic acid. 2. The method according to claim 1, wherein the acid in step (1) is selected from hydrochloric acid, formic acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid, fluorine at least one of silicic acid, ethylsulfonic acid and perchloric acid; Preferably, the acid in 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 acetic acid, hydrofluoric acid, methanesulfonic acid, sulfamic acid at least one of acid and fluorosilicic acid; Preferably, the molar ratio of the first acid and the second acid is 2-100:1, more preferably 9-50:1; Preferably, the concentration of the acid solution in step (1) is 0.1-15 mol·L ^-1 , more preferably 0.5-6 mol·L ^-1 ; Preferably, relative to 1 g of the cracked carbon black, the amount of the acid solution in step (1) is 5-20 mL, more preferably 10-15 mL. 3. The method according to claim 1 or 2, characterized in that, the conditions for the first contact in step (1) include: the temperature is 20-80°C, and the time is 10-600min; preferably, the temperature is 40-80°C 60℃, the time is 60-300min; Preferably, the first contact in step (1) is carried out under stirring conditions, further preferably, the stirring speed is 50-1000 rpm, preferably 200-800 rpm; Preferably, the method further comprises: recovering the hydrogen sulfide waste gas produced by the first contacting in step (1) using lye and/or soda lime. 4. The method according to any one of claims 1-3, wherein a carbon black surfactant is also introduced in the first contact 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 selected from at least one of monofluoroacetic acid, difluoroacetic acid, trifluoroacetic acid and hydrogen peroxide, and relative to 100 parts by weight of the cracked carbon black, the surface of the carbon black The added amount of the activator is 0.5-6 parts by weight, preferably 1-4 parts by weight; Preferably, the carbon black surfactant is oxygen, and relative to 100 g of the pyrolysis carbon black, the oxygen flow rate is 10-1000 mL/min, preferably 30-500 mL/min. 5. The method according to any one of claims 1-4, wherein the concentration of the solution containing fluorosilicic acid is 0.5-60% by weight, preferably 5-35% by weight; Preferably, relative to 1 g of the first carbon black containing silicon compound, the amount of the solution containing fluorosilicic acid in step (2) is 5-20 mL, more preferably 10-15 mL; Preferably, the conditions for the second contact in step (2) include: the temperature is 20-80°C, and the time is 10-600min; further preferably, the temperature is 50-60°C, and the time is 60-480min; Preferably, the second contact in step (2) is carried out under stirring conditions, further preferably, the stirring speed is 50-1000 rpm, preferably 300-800 rpm. 6. The method according to any one of claims 1-5, wherein the solution containing fluorosilicic acid also contains hydrofluoric acid; Preferably, in the solution containing fluorosilicic acid, the content of fluorosilicic acid is 15-50 wt %, and the content of hydrofluoric acid is 1-20 wt %; more preferably, the content of fluorosilicic acid is 20-35 wt % % by weight, the content of hydrofluoric acid is 2-15% by weight; Further preferably, at least part of the fluorosilicic acid-containing solution is provided by a fluorine-containing waste acid solution obtained from a phosphate fertilizer production process. 7. The method according to any one of claims 1-6, wherein the purification in step (3) comprises: mixing the second filtrate with lead fluorosilicate and calcium fluorosilicate to remove the first Sulfate and fluoride ions in the second filtrate. 8 . The method according to claim 1 , wherein the pyrolysis carbon black is obtained by pyrolysis of waste tires. 9 . 9. The method according to any one of claims 1-8, characterized in that, optionally, the method further comprises: before step (1), the cracked carbon black is subjected to pretreatment for removing colloid layer . 10. The method according to claim 9, wherein the pretreatment for removing the colloid layer comprises: 1) grinding the pyrolysis carbon black; 2) high temperature carbonization is carried out with the cracked carbon black obtained by grinding; Preferably, the grinding time is 0.1-1.5h; Preferably, the particle size of the cracked carbon black obtained by grinding is 160-500 mesh; Preferably, the conditions for the high-temperature carbonization include: performing in an inert atmosphere, the temperature is 600-800° C., and the time is 0.1-3 h.