CN105819517B - A kind of method using coal ash for manufacturing for iron oxide red - Google Patents

Abstract

The invention belongs to Environmental Chemistry field, discloses a kind of method using coal ash for manufacturing for iron oxide red.This method comprises the following steps：(1) acidleach：Flyash is extracted using acid solution, obtains pickle liquor；(2) extract：The pickle liquor is extracted using extraction organic phase, obtains extract；(3) it is stripped：Gained extract is stripped using strippant, obtains anti-stripping agent；(4) it is concentrated by evaporation：By anti-stripping agent evaporation, concentration, crystallization；(5) calcine：Iron oxide red is made in the crystallization calcining.The inventive method is made iron oxide red, by flyash utilization of waste as resource, improves the utilization rate of valuable metal in flyash, solve environmental problem using flyash as raw material；The extractant used can recycle, and reduce the cost of industrialized production；Obtained iron oxide red product quality is high, and purity reaches the requirement of the product technologies of GB 1,863 2008 more than 95%.

Description

A kind of method utilizing fly ash to prepare iron oxide red

technical field

The invention belongs to the field of environmental chemistry, in particular to a method for preparing iron oxide red from fly ash.

Background technique

Fly ash is the powdery ash collected from the flue gas of coal-fired boilers. It is called "fly ash" or "finely ground fuel ash" in foreign literature. It is the main industrial solid waste produced by coal-fired power plants. The main chemical components of fly ash are SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , etc. and unburned carbon, as well as some trace elements and rare elements. For quite a long time, coal will still be the main energy source in our country. At present, in my country's primary energy structure, coal accounts for more than 50%, of which 70% is used for coal-fired power generation. According to relevant statistics, the output of fly ash in my country reached 375 million tons in 2009, and 700 million tons in 2010. It is estimated that by 2020, the total accumulated stock of fly ash in my country will reach 3 billion tons. If the huge amount of fly ash is not used rationally, it will not only occupy a large amount of land resources, but also cause various pollutions such as soil, water and air, directly or indirectly endangering human health and biological survival. Therefore, the comprehensive utilization of fly ash is particularly important.

At present, the main ways of using fly ash include making building materials, filling pits and building roads, improving soil, and treating waste water and waste gas. However, these utilization approaches have not made effective use of the valuable metal ions in fly ash. Since the mass fraction of alumina in fly ash is 15-40%, it is an excellent resource for preparing alumina. In the process of preparing alumina by fly ash acid method, since fly ash contains a large amount of iron, it is necessary to effectively separate aluminum and iron, and the separated aluminum is used to make alumina. In order to further improve the utilization of valuable metals in fly ash, the present invention directly prepares iron oxide red from iron obtained after separation.

Iron oxide red, also known as iron red or iron oxide red, has a chemical formula of α-Fe ₂ O ₃ . It is a traditional and important inorganic pigment, and it is also the most stable compound among iron oxides. Iron oxide red has high coloring strength, acid and alkali resistance, high purity, and good thermal stability. It is widely used in magnetic materials, coatings, catalysis, and biomedical industries, and has a broad market. At present, the methods for preparing iron oxide red at home and abroad can be mainly divided into two categories: dry method and wet method. The dry method mainly includes roasting method, thermal decomposition method, and Lu method. Wet methods mainly include sulfate method, nitrate method, mixed salt method, etc.; in addition, there are process improvement methods such as hydrothermal method, catalytic method, and nucleation method. Among them, the roasting method is to make iron oxide red by calcining ferrous sulfate at high temperature. This process has high energy consumption and low product purity. (Fe(CO) ₅ ) or ferrocene (FeCP ₂ ) as raw materials, prepared by gas phase decomposition, flame thermal decomposition or laser decomposition, etc., this process technology is difficult, and the one-time investment is also large; sulfate method, The process of nitrate method and mixed salt method is: first make the seed crystal, then put the seed crystal into the reaction tank filled with Fe ²⁺ solution, and add iron filings in it, and keep the temperature at 75-85°C , feed oxygen (or air), oxidize Fe ²⁺ into Fe ³⁺ , then combine with OH ^- in water and deposit on the surface of the seed crystal, and gradually form iron oxide red. During the oxidation reaction, hydrogen ions are also generated, and the hydrogen ions interact with metals to generate Fe ²⁺ and be oxidized to Fe ³⁺ . This cycle is repeated until the oxidation reaction ends. Then, filter the precipitate and dry it at 300-400°C to obtain the product.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the above-mentioned prior art, the primary purpose of the present invention is to provide a method for preparing iron oxide red from fly ash. The method of the present invention takes fly ash as raw material, and obtains iron oxide red through extraction, stripping, crystallization and calcination, which not only utilizes fly ash waste as a resource, improves the utilization rate of valuable metals in fly ash, but also It provides a new way for the utilization of fly ash, solves environmental problems, and also brings economic benefits; the extractant can be recycled, which reduces the cost of industrial production; the obtained iron oxide red product is of high quality and has a purity of more than 95%. , up to GB 1863-2008 product technical requirements.

The object of the present invention is achieved through the following solutions:

A kind of method utilizing fly ash to prepare iron oxide red, comprises the following steps:

(1) acid leaching: use an acidic solution to extract the fly ash to obtain an acid leaching solution;

(2) Extraction: use extraction organic to extract relative to the acid dipping solution to obtain the extract;

(3) stripping: using a stripping agent to strip the obtained extract to obtain a strip;

(4) Evaporating and concentrating: evaporating, concentrating and crystallizing the stripping solution;

(5) Calcining: Calcining the crystals to obtain iron oxide red.

The acidic solution described in step (1) can be hydrochloric acid solution or sulfuric acid solution.

Preferably, the acidic solution described in step (1) is a hydrochloric acid solution.

More preferably, the acidic solution in step (1) is a hydrochloric acid solution with a concentration of 2-6 mol/L.

Most preferably, the acidic solution described in step (1) is a hydrochloric acid solution with a concentration of 4 mol/L.

Preferably, the mass ratio of acid solution and fly ash used in step (1) is 3:1˜1:3.

More preferably, the mass ratio of acid solution and fly ash used in step (1) is 1:1.

Preferably, the extraction time in step (1) is 3-10 hours.

More preferably, the extraction time in step (1) is 5 hours.

Preferably, the extracted organic phase described in step (2) includes at least one of N503, TBP and TRPO.

More preferably, the extracted organic phase in step (2) also includes kerosene.

Most preferably, the extracted organic phase in step (2) includes N503, TBP and kerosene, and its volume ratio is N503:TBP:kerosene=2:1:2.

Preferably, the volume ratio of the extracted organic phase to the pickling solution in step (2) is 1:2-3:1.

More preferably, the volume ratio of the extracted organic phase to the pickling solution in step (2) is 1:1.

Preferably, the extraction time in step (2) is 2 to 10 minutes.

More preferably, the extraction time described in step (2) is 5 minutes.

The extracted raffinate in step (2) can be used to make alumina.

Preferably, the stripping time in step (3) is 2 to 10 minutes.

More preferably, the time of stripping described in step (3) is 4 minutes.

Preferably, the stripping agent described in step (3) can be an oxalic acid solution.

More preferably, the stripping agent in step (3) is an oxalic acid solution with a concentration of 0.25-1.0 mol/L.

Most preferably, the stripping agent described in step (3) is an oxalic acid solution with a concentration of 0.75mol/L.

Preferably, the volume ratio of the stripping agent to the extract in step (3) is 1:2-3:1.

More preferably, the volume ratio of the stripping agent to the extract in step (3) is 1:1.

The unloaded extracted organic phase after stripping in step (3) can be recycled.

Preferably, the evaporation in step (4) is carried out at a temperature of 80-110°C.

More preferably, the evaporation in step (4) is carried out at a temperature of 105°C.

Preferably, the calcination in step (5) refers to calcination at a temperature of 300-500° C. for 1-4 hours.

Most preferably, the calcination in step (5) refers to calcination at a temperature of 400° C. for 1 to 4 hours.

Mechanism of the present invention is:

The method of the present invention takes fly ash as raw material, and obtains iron oxide red through extraction, stripping, crystallization and calcination, which not only utilizes fly ash waste as a resource, improves the utilization rate of valuable metals in fly ash, but also It provides a new way for the utilization of fly ash, solves environmental problems, and also brings economic benefits; the extractant can be recycled, which reduces the cost of industrial production; the obtained iron oxide red product is of high quality and has a purity of more than 95%. , up to GB 1863-2008 product technical requirements.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention uses fly ash as raw material to prepare iron oxide red, which not only improves the utilization of valuable metals in fly ash, provides a new way for fly ash utilization, solves environmental problems, but also brings economic benefits. benefit.

(2) The general wet method for preparing iron oxide red products is all to make the precipitate earlier, then filter and wash to obtain the intermediate product, and then carry out the next step operation, but in the present invention, oxalic acid is used as the back extraction agent, and the back raffinate The iron oxide red product can be directly concentrated and calcined, eliminating the need for intermediate links such as filtration and washing, and the preparation process is simple; the condition parameters of each step in the preparation method are easy to control, the preparation efficiency is high, and it is convenient for industrial production.

(3) The extraction system in the present invention has high-efficiency selectivity (good extraction effect for iron (Ⅲ), no extraction for aluminum (Ⅲ)), good separation effect, and the extraction agent can be recycled, reducing industrial production the cost of.

(4) The iron oxide red product prepared by the present invention has high quality and a purity of over 95%, meeting the product technical requirements of GB 1863-2008.

Description of drawings

Fig. 1 is the process flow chart of preparation method of the present invention.

Figure 2 is the XRD pattern of the sample of Example 1.

Figure 3 is the XRD pattern of the sample of Example 2.

Fig. 4 is the SEM figure of the sample of embodiment 1.

Fig. 5 is the SEM figure of the sample of embodiment 2.

detailed description

The present invention will be further described in detail below with reference to the examples and drawings, but the implementation of the present invention is not limited thereto.

Example 1

A kind of preparation method of iron oxide red, process flow diagram is shown in Fig. 1, and its concrete preparation steps are as follows:

(1) Soak 1 mass part of fly ash in 1 mass part of 4mol/L hydrochloric acid solution for 5 hours, then remove the filter residue to obtain acid dipping solution.

(2) The extraction organic phase of 1 volume part of N503+TBP+kerosene composition is placed in the extraction reactor and mixed with 1 volume part of the pickling solution, wherein the volume ratio of N503:TBP:kerosene is 2:1:2, extraction The volume ratio of the organic phase to the pickling solution is 1:2, then vibrate for 5 minutes, separate the phases and keep the extract.

(3) the oxalic acid solution of 1 volume part 0.75mol/L is placed in the extraction reactor as back extraction agent and 1 volume part extraction liquid in step (2) and mixes, and wherein the volume ratio of back extraction agent and extraction liquid is 1 : 1, then shake and contact for 4min, static phase separation, the unloaded organic phase after phase separation is recycled, and the stripping solution is retained.

(4) Place the stripping solution in step (3) in an evaporation device, evaporate, concentrate, and crystallize at 105°C; then place the crystals in a muffle furnace for calcination, and calcinate at 400°C for 1.5h, Obtain iron oxide red product.

Example 2

(1) Soak 1 mass part of fly ash in 1 mass part of 4mol/L hydrochloric acid solution for 5 hours, then remove the filter residue to obtain acid dipping solution.

(2) The extraction organic phase of 1 volume part of N503+TBP+kerosene composition is placed in the extraction reactor and mixed with 1 volume part of the pickling solution, wherein the volume ratio of N503:TBP:kerosene is 2:1:2, extraction The volume ratio of the organic phase to the pickling solution is 1:1, then vibrate and contact for 5 minutes, then separate the phases at rest, and retain the extract.

(3) the oxalic acid solution of 1 volume part 0.75mol/L is placed in the extraction reactor as back extraction agent and 1 volume part extraction liquid in step (2) and mixes, and wherein the volume ratio of back extraction agent and extraction liquid is 1 : 1, then shake and contact for 4min, static phase separation, the unloaded organic phase after phase separation is recycled, and the stripping solution is retained.

(4) Place the stripping solution in step (3) in an evaporator, evaporate, concentrate, and crystallize at 105°C; then place the crystal in a muffle furnace and calcinate at 400°C for 2 hours to obtain iron oxide red product.

Example 3

(1) Soak 1 mass part of fly ash in 1 mass part of 4mol/L hydrochloric acid solution for 5 hours, then remove the filter residue to obtain acid dipping solution.

(2) The extraction organic phase of 1 volume part of N503+TBP+kerosene composition is placed in the extraction reactor and mixed with 1 volume part of the pickling solution, wherein the volume ratio of N503:TBP:kerosene is 2:1:2, extraction The volume ratio of the organic phase to the pickling solution is 3:1, then vibrate and contact for 5 minutes, then separate the phases at rest, and retain the extract.

(3) the oxalic acid solution of 1 volume part 0.75mol/L is placed in the extraction reactor as back extraction agent and 1 volume part extraction liquid in step (2) and mixes, and wherein the volume ratio of back extraction agent and extraction liquid is 1 : 1, then shake and contact for 4min, static phase separation, the unloaded organic phase after phase separation is recycled, and the stripping solution is retained.

(4) Place the stripping solution in step (3) in an evaporator, evaporate, concentrate, and crystallize at 105°C; then place the crystal in a muffle furnace and calcinate at 400°C for 2 hours to obtain iron oxide red product.

Embodiment 4: Carry out performance and structure test to the iron oxide red product of embodiment gained:

(1) Crystal structure

The phase composition of the iron oxide red product obtained in Examples 1 and 2 was tested with a MSALXD XRD analyzer, and the results are shown in Figures 2 and 3. As can be seen from the figure, the characteristic peaks of the product spectrograms obtained in Examples 1 and 2 are basically consistent with the characteristic peaks of the standard spectrograms. Therefore, the product that the inventive method makes is iron oxide red.

(2) Surface structure

The iron oxide red products obtained in Examples 1 and 2 were scanned with an XL30ESEM scanning electron microscope (Philips of the Netherlands), and the results are shown in Figures 4 and 5. As can be seen from the figure, the microscopic particles of the products obtained in Examples 1 and 2 are in the shape of a sphere and are at the nanoscale.

(3) Other features

According to the analysis and determination method of iron oxide pigment GB/T 1863-2008, the iron oxide red products obtained in Examples 1 and 2 were tested for technical indicators such as color, purity, pH value of aqueous suspension, and loss on drying. The results are shown in Table 1.

Table 1 embodiment gained iron oxide red product technical index result

It can be seen from Table 1 that the red iron content (calculated as Fe ₂ O ₃ ) of the iron oxide prepared by this method can reach 98.68%, which has reached the product technical requirements of iron oxide pigment (GB/T 1863-2008).

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (6)

1. a method utilizing fly ash to prepare iron oxide red is characterized in that comprising the following steps: (1) acid leaching: use an acidic solution to extract the fly ash to obtain an acid leaching solution; (2) Extraction: use extraction organic to extract relative to the acid dipping solution to obtain the extract; (3) stripping: using a stripping agent to strip the obtained extract to obtain a strip; (4) Evaporating and concentrating: evaporating, concentrating and crystallizing the stripping solution; (5) calcining: calcining the crystals to obtain iron oxide red; The extraction organic phase described in step (2) comprises N503, TBP and kerosene, and its volume ratio is N503:TBP:kerosene=2:1:2; Stripping agent described in step (3) is oxalic acid solution; The acidic solution described in the step (1) is hydrochloric acid solution; The mass ratio of used acidic solution and fly ash is 1:1; The time of described leaching is 5 hours; The time of stripping described in step (3) is 4 minutes; Described stripping agent is the oxalic acid solution that concentration is 0.25～1.0mol/L; The volume ratio of described stripping agent and described extraction liquid is 1:1; Stripping agent described in step (3) is the oxalic acid solution that concentration is 0.75mol/L; The purity of the obtained iron oxide red is more than 95%. 2. the method utilizing fly ash to prepare iron oxide red according to claim 1, is characterized in that: the volume ratio of extraction organic phase described in step (2) and described pickling liquid is 1:2～3: 1; the extraction time is 2 to 10 minutes. 3. the method utilizing fly ash to prepare iron oxide red according to claim 1, is characterized in that: the volume ratio of extraction organic phase described in step (2) and described pickling solution is 1:1; The extraction time was 5 minutes. 4. The method for preparing iron oxide red from fly ash according to claim 1, characterized in that: the evaporation in step (4) is carried out at a temperature of 80-110°C. 5 . The method for preparing iron oxide red from fly ash according to claim 1 , wherein the calcination in step (5) refers to calcination at a temperature of 300-500° C. for 1-4 hours. 6. the method utilizing fly ash to prepare iron oxide red according to claim 1, is characterized in that: acidic solution described in step (1) is the hydrochloric acid solution that concentration is 4mol/L; Described in step (4) Evaporation is carried out at a temperature of 105° C.; the calcination in step (5) refers to calcination at a temperature of 400° C. for 1 to 4 hours.