CN111519019B

CN111519019B - Method for desiliconizing hydrated oxide valuable element during leaching

Info

Publication number: CN111519019B
Application number: CN202010502011.5A
Authority: CN
Inventors: 刘召波; 付云枫; 王玮玮; 李晓艳; 韩国强
Original assignee: China ENFI Engineering Corp
Current assignee: China ENFI Engineering Corp
Priority date: 2020-06-04
Filing date: 2020-06-04
Publication date: 2022-02-08
Anticipated expiration: 2040-06-04
Also published as: CN111519019A

Abstract

The invention discloses a desiliconization method for leaching valuable elements of hydrated oxides. The method comprises the following steps: s1, carrying out dehydration treatment and slag crushing treatment on the hydrated oxide slag; s2, drying and eroding, namely adding sulfuric acid and water into the hydrated oxide slag, and realizing the first generation of the filtering silicon coagulation body by controlling the concentration of the sulfuric acid, the addition amount of the water, the reaction temperature and the stirring and grinding strength; s3, adding water to make the first generated filterable silicon coagulation body and the incompletely reacted lump material react for the second time to generate filterable silicon coagulation body; and S4, adding a cosolvent to improve the ionic strength of the system and strengthen the coagulation behavior of the soluble silicon, then diluting to a set solid-liquid ratio, and carrying out solid-liquid separation. By applying the technical scheme of the invention, valuable elements in the slag can be leached, and the leaching of impurity silicon elements is inhibited.

Description

Method for desiliconizing hydrated oxide valuable element during leaching

Technical Field

The invention relates to the technical field of hydrometallurgy, in particular to a desiliconization method during leaching of valuable elements of hydrated oxides.

Background

At present, methods for removing silicon during leaching of valuable elements in hydrated oxide slag can be divided into a chemical coagulation method, a cation exchange method, an electrocoagulation method, a reverse osmosis membrane method, a neutralization flocculation method, a crystallization precipitation method and an acid roasting method. The chemical coagulation method utilizes metal hydroxide and silicon flocculation adsorption to achieve the aim of desiliconization, common silicon-removing coagulation agents comprise a magnesium agent, an aluminum agent and an iron agent, and the method is generally effective in neutral solution and cannot be applied to acidic solution. The ion exchange method is more suitable for deep silicon removal and is not suitable for high salt solution. The electrocoagulation method can not only remove silicon, but also remove turbidity, decoloration, heavy metal ions, algae, bacteria and organic matters in water, but has higher silicon removal treatment cost. The reverse osmosis membrane process can effectively remove colloidal or dissolved silicon from the solution, but requires strict pretreatment of the feed water. The neutralization flocculation method separates leaching and silicic acid coagulation steps, and is not suitable for direct desiliconization of acid leaching solution. Common desilication processes include the Vieille-Montagne process, the EZ process, and the Radina method. Among the processes, the Vieille-Montagne process in the old mountain has the defect of long time for removing silicon by slow crystallization; the EZ process has the defects that a flocculating agent needs to be added additionally, and the flocculation temperature needs to be stabilized or controlled; the Radina process has the disadvantages of complicated process and the need for additional flocculant addition. The crystallization precipitation method comprises a Vieille-Montagne process, an EZ process and a Radina method which are not applied to desilication of the ferro-aluminum slag leaching solution, and all parameters and feasibility are determined by tests. The acid roasting method can theoretically suppress the leaching of silicon in slag, but high energy consumption is a main reason limiting the application thereof.

Disclosure of Invention

The invention aims to provide a desiliconization method for leaching valuable elements of hydrated oxides, which is used for realizing low-cost desiliconization of the valuable elements of hydrated oxide slag during leaching.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for desiliconizing a hydrated oxide as it is leached of valuable elements. The method comprises the following steps: s1, carrying out dehydration treatment and slag crushing treatment on the hydrated oxide slag; s2, drying and eroding, namely adding sulfuric acid and water into the hydrated oxide slag, and realizing the first generation of the filtering silicon coagulation body by controlling the concentration of the sulfuric acid, the addition amount of the water, the reaction temperature and the stirring and grinding strength; s3, adding water to make the first generated filterable silicon coagulation body and the incompletely reacted lump material react for the second time to generate filterable silicon coagulation body; and S4, adding a cosolvent to improve the ionic strength of the system and strengthen the coagulation behavior of the soluble silicon, then diluting to a set solid-liquid ratio, and carrying out solid-liquid separation.

Further, the hydrated oxide slag includes oxyhydroxide and hydroxide gels; preferably, the hydrated oxide slag is hydrated iron oxide aluminum slag.

Further, in S1, the hydrated oxide slag is dehydrated to reduce the moisture to 5% to 70%, preferably, 30% to 60%.

Further, in S1, the dehydrated slag is subjected to a crushing treatment so that the particle size of the gel slag is less than or equal to 10 cm.

Further, a dense tank, a filter press or drying equipment is adopted to dehydrate the hydrated oxide slag.

Further, in S2, the total water content of the drying alteration process control system is less than or equal to 80%, the concentration of sulfuric acid is 20% to 98%, and preferably 30% to 65%; the reaction temperature is 25-300 ℃, and preferably 40-95 ℃; the stirring intensity standard is that the materials are prohibited from crusting into big balls or blocks, and the particle size of the materials is controlled to be less than or equal to 5 mm; the reaction time is 0.5-2 h.

Further, in S4, water is added until the solid-to-liquid ratio is set to be 1: 0.5-1: 4kg/L, preferably 1: 1-1: 3kg/L, and the filterable silicon precipitate is generated by secondary reaction.

Furthermore, in S4, a cosolvent is added, and the total ionic strength of the system after reaction is ensured to be more than or equal to 10mol/L, and the ionic strength of the system after reaction is preferably more than 15 mol/L; the cosolvent is a reducing agent or inorganic salt; the reaction time is 0.5 h-2 h; the reaction temperature is 25 ℃ to 90 ℃, preferably 35 ℃ to 70 ℃.

Further, when the hydrated oxidation slag has no physical inclusion weak contact and chemical encapsulation, S2, S3 and S4 are continuously performed.

By applying the technical scheme of the invention, valuable elements in the slag can be leached, and the leaching of impurity silicon elements is inhibited. The desiliconization technology of hydroxide or oxyhydroxide acid leachate is a common technology in the field of hydrometallurgy, and can be used for reference in desiliconizing and leaching of other similar hydrated oxide slag. Besides avoiding the generation of dirt among phases, the desiliconization leaching solution can also improve the filtering performance of the pickle liquor. In addition, the production cost is increased because the current workshop leaching process does not need to be changed on a large scale or large and medium equipment does not need to be additionally added; the subsequent extraction behavior is not influenced or the water treatment difficulty is increased due to the fact that an inorganic organic flocculant is not required to be added into the leaching solution; in addition, the method has no roasting step, and has no problems of acid mist and energy consumption.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic diagram of a desilication process for leaching valuable elements of hydrated oxides according to an embodiment of the present invention;

FIG. 2 shows a schematic diagram of desilication of a hydrous oxide during leaching of valuable elements according to the invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

Aiming at various technical problems of desilication in the process of leaching valuable elements of hydrated oxides mentioned in the background technology, the invention provides the following technical scheme to realize low-cost desilication in the process of leaching valuable elements of hydrated oxides.

According to an exemplary embodiment of the present invention, a method for desilication of hydrated oxides during leaching of valuable elements is provided. The method comprises the following steps (see fig. 1): s1, carrying out dehydration treatment and slag crushing treatment on the hydrated oxide slag; s2, drying and changing, namely adding sulfuric acid and water into the dehydrated hydrated oxide slag, and realizing the first generation of the filterable silicon coagulation body by controlling the concentration of the sulfuric acid, the addition amount of the water (controlling the total water content of the system), the lowest reaction temperature and the stirring and grinding strength; s3, adding water (proper amount) to make the lump materials react for the second time to generate the filtering silicon settlement body when the filtering silicon settlement body is generated for the first time, and then diluting to the set solid-liquid ratio; and S4, adding a cosolvent to enhance leaching of the target valuable elements, and then carrying out solid-liquid separation.

The hydrated oxide slag comprises hydroxide oxide gel and hydroxide gel, free amorphous soluble silicon in the slag is flocculated and adsorbed in the hydroxide oxide gel and the hydroxide gel during precipitation and enrichment, and the hydrated oxide slag is typically hydrated iron oxide aluminum slag.

In an exemplary embodiment of the invention, the following is true. If the moisture content is too low, too much energy is consumed for drying in S1, the moisture content may be reduced by 60% or less by subjecting the hydrous oxide slag to dehydration treatment, and if the moisture content is too low, too much energy is consumed for drying, the moisture content is preferably reduced to 5% to 70%, more preferably 30% to 60%. In one embodiment of the invention, the hydrated oxide slag is dehydrated by a dense tank, a filter press or drying equipment.

According to an exemplary embodiment of the present invention, the total water content of the drying alteration process control system is less than or equal to 80%, and the concentration of sulfuric acid is 20% to 98%, preferably 30% to 65%; the reaction temperature is 25-300 ℃, and preferably 40-95 ℃; the stirring intensity standard is that the materials are prohibited from crusting into big balls or blocks, and the particle size of the materials is controlled to be less than or equal to 5 mm; the reaction time is 0.5-2 h. Water content and reaction temperature are controlled by adding water, and a stirring blade or a mill is easily damaged due to overhigh temperature.

Preferably, in S4, water is added until the solid-liquid ratio is set to be 1: 0.5-1: 4kg/L, preferably, the solid-liquid ratio is 1: 1-1: 3, and the filterable silicon precipitate is generated through secondary reaction.

In an embodiment of the invention, in S4, a reducing agent or an inorganic salt cosolvent is added, and the total ionic strength of the system after reaction is ensured to be greater than or equal to 10mol/L, and the optimal value of the ionic strength of the system after reaction is more than 15 mol/L; the reaction time is 0.5h to 2 h; the reaction temperature is 25 ℃ to 90 ℃; finally diluting to a set solid-liquid ratio or concentration value, and carrying out solid-liquid separation.

According to a typical embodiment of the invention, when the hydrated oxidation slag has no physical inclusion weak contact and chemical coating (the physical inclusion weak contact refers to precipitation of hydroxyl oxide physically coated with included soluble silicon, and the chemical coating refers to variable-valence metal hydroxyl oxide coated soluble silicon), S2, S3 and S4 can be continuously carried out, but can not be combined into a rapidly finished step, otherwise, the risk of groove and material plate combination and the like is easily generated, and the implementation of technical engineering is extremely unfavorable. Aiming at soluble silicon in the hydrated oxidation slag, the steps are an integral process, so that the drying alteration effect under the conditions of specific acidity and ionic strength is realized, and the filtering silicon settlement body is generated. The step S2 aims at the action of exposed amorphous soluble silicon, the step S3 enhances the action of physically weak contact amorphous soluble silicon in the process of dry etching, and the step S4 mainly aims at the action of chemically wrapped valuable elements and amorphous soluble silicon. When the hydrated oxide slag is treated in the presence of physical weak contact and chemical encapsulation, S2, S3 and S4 cannot be combined.

In addition, in S4, a cosolvent is added to further enhance leaching of the target valuable element, and after a part of the variable-valence metals such as manganese and the like are oxidized to a high-valence state, a cosolvent such as a reducing agent needs to be further added to reduce the valence of the target valuable element for leaching; while inhibiting leaching of other metals such as chromium.

Description of the principle:

dry digestion is one of the anaerobic digestions and differs from wet digestion primarily in the amount of dry or total solids in the digester. Dry digestion occurs when the total solids is greater than 15% in a discontinuous digester. Similarly, in the hydrated oxide slag leaching process, leaching with less than 85% of the total water in the system is referred to as a dry digestion process. The hydrated oxide slag and the solvent are dissolved due to chemical reaction, and the dissolution process of the hydrated oxide slag under the acidic condition can be described by 'alteration'. The alteration is from geology, and refers to the process that rock or mineral is subjected to hydrothermal action and generates physicochemical reaction, so that the structure, structure and composition of the original rock are correspondingly changed to generate new mineral combination. The dissolution of oxide slag and the reformation of dissolved products into a new phase at the reaction interface is analogous to a "change".

During leaching, the silicon is at pH<2 in dilute acid solution, the product is mostly H₄SiO₄And H₅SiO₄ ⁺The reaction product can be reacted with hydroxyl to generate disilicic acid with the coordination number of silicate radical of 6, then polysilicic acid such as trisilicic acid is generated, and finally SiO is formed by polymerization₂The sol is represented by the reaction formula (1). In SiO₂In the sol, silicic acid continues to polymerize, gelation occurs to form gel, and part of water is trapped inside the gel, as shown by the product structure in formula (1) and the silica gel in figure 2. It is concluded through condition tests that the gelation time is closely related to pH or acidity, the silicic acid polymerization reaction rate is fast in an acidic solution with a large pH value, and gelation phenomenon occurs to deteriorate leaching and solid-liquid separation of other valuable elements in the slag.

The following examples are provided to further illustrate the advantageous effects of the present invention.

Example 1

TABLE 1 Bayer Red mud composition table (%)

The experiment of drying, alteration and silicon removal of the red mud comprises the following steps: the red mud is pretreated and dried until the water content is lower than 10%, and the specific components are shown in table 1. Drying alteration is carried out at the following reaction temperature or sulfuric acid concentration, secondary alteration and dilution leaching are combined, the water adding rate is controlled (20min is finished) when water is added for dilution, and solid-liquid separation is carried out after the reaction is carried out for 20 min. The intensity of the agitation was 100rpm, and no large pellets were formed.

Table 2 shows the leaching rate (%) of each element in red mud under different sulfuric acid concentrations, the solid-to-liquid ratio is 1:3, the total time of one-time alteration is 1h, the leaching reaction temperature is 60 ℃, and the red mud is diluted to the solid-to-liquid ratio of 1:4 and then filtered. Since the soluble silicon in the red mud is mainly the sodium aluminum silicate product, and the physical inclusion of other compounds and the chemical encapsulation of the valence-variable metal oxyhydroxide are basically not existed, the steps S2, S3 and S4 can be carried out more continuously.

Table 3 shows that the leaching rate (%) of each element in the red mud is 1:3 in solid-liquid ratio, 1h in total time of one-time alteration and 600g/L in sulfuric acid concentration under different drying alteration temperature conditions, and the red mud is diluted to 1:4 in solid-liquid ratio and then filtered.

Example 2

The drying, alteration and desilicication experiment of the iron-aluminum slag comprises the following steps: the water content of the iron-aluminum slag after pretreatment is 5%, and the components are shown in Table 4; the water is pre-added for 2.7m in the container³2.2t of sulfuric acid (with the concentration of 93%) for processing industry, 1.3t of pretreated iron-aluminum slag (the charging time is 30min), then reacting for 15min, then adding 1.4t of acid, reacting for 15min, adding 1.3m of water³Adding 1.3t of material (the adding time is 30min), adding 0.7t of acid and 1.3t of material (the adding time is 30min), and reacting for 80min to finish the first silicon coagulation formation of the dry alteration. Slowly adding water until the solid-to-liquid ratio is 1:4t/m³And finishing the generation and dilution of secondary silicon coagulation body, and then carrying out solid-liquid separation. Each elementThe results of the leaching are shown in table 5. The intensity of the agitation was 100rpm, and no large pellets were formed.

Table 4 iron and aluminum slag composition (%) -for this experiment

TABLE 5 extraction ratio (%)

Example 3

The drying, alteration and desilicication experiment of the iron-aluminum slag comprises the following steps: adding 100g of dry raw materials (the components are shown in Table 4) and 120mL of 50% sulfuric acid to generate a silicon polymer precipitate for the first time; stirring and grinding intensity is sufficient, 100-150 rpm, and reaction is carried out for 1 h. And then adding water to the volume of 200mL, carrying out secondary generation of silicon precipitates, fully stirring and grinding the mixture at the speed of 250-300 rpm, and reacting for 20 min. Then adding water to dilute the mixture to 350mL, reacting for 10min, adding 50g of sodium metabisulfite to enhance leaching (adding time is 30min), reacting for 30min, and then carrying out solid-liquid separation. The results of the experiment are shown in Table 6.

TABLE 6 leaching rate (%)

Example 4

The No. 6 ferroaluminum slag (main components are shown in Table 7) had a water content of 50% after pretreatment. Leaching under the conditions of pH 2 and liquid-solid ratio of 1:4g/mL for 2h and stirring intensity of 300 rpm. The leaching results of each element at different leaching temperatures are shown in table 8, and the leaching concentrations of silicon ions in the table are higher than 500ppm under each condition, which can seriously affect the subsequent valuable element extraction process.

TABLE 76 iron and aluminium slag main chemical composition

TABLE 86 No. iron-aluminium slag non-alteration desiliconization leaching condition

Example 5

The water content of the ferroaluminum slag was 70% without pretreatment, and the components after drying are shown in Table 4. The water is pre-added for 1.8m in the container³1.3t of sulfuric acid for processing industry, 2.5t of untreated iron-aluminum slag (feeding time is 30min), then reacting for 15min, then adding 0.26t of acid, and reacting for 15min to finish the generation of the first silicon coagulation body by drying and alteration. Slowly adding water until the solid-to-liquid ratio is about 1:4t/m³And finishing the generation and dilution of secondary silicon coagulation body, and then carrying out solid-liquid separation. The leaching results of each element are shown in table 9. The intensity of the agitation was 100rpm, and no large pellets were formed.

TABLE 9 extraction ratio (%)

Example 6

The chemical composition of the fresh iron-aluminum slag is shown in Table 10. The newly-prepared iron-aluminum slag is dried in an oven for 0.5-1 h to obtain the iron-aluminum slag with the target water content, as shown in Table 11. 240g of medium-concentrated hydrochloric acid is added into two kinds of slag with different water contents (measured by dry materials) of 200g once within 30 min. The temperature is 90 ℃ during feeding, the leaching time is about 2.5h, the temperature is 100 ℃ during leaching, the volume of diluted ore pulp is about 800mL, 90g of sodium sulfite reducing agent is added, the temperature is lower than 80 ℃, the time is more than or equal to 30min, the solid-liquid separation is carried out after the reaction is carried out for 30min, and the experimental results are shown in Table 12.

TABLE 10 fresh IRON-ALUMINIUM SLAG CHEMICAL COMPONENTS (%)

TABLE 11 moisture content of dried wet material and weight of wet material

TABLE 12 silicon-containing case of the filtrates

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: the production cost is increased because the current workshop leaching process does not need to be changed on a large scale or large and medium equipment does not need to be additionally added; the subsequent extraction behavior is not influenced or the water treatment difficulty is increased due to the fact that an inorganic organic flocculant is not required to be added into the leaching solution; in addition, the method has no roasting step, and has no problems of acid mist and energy consumption.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for desiliconizing hydrated oxide slag during valuable element leaching is characterized by comprising the following steps:

s1, carrying out dehydration treatment and slag crushing treatment on the hydrated oxide slag;

s2, drying and eroding, namely adding sulfuric acid and water into the hydrated oxide slag, and realizing the first generation of the filtering silicon coagulation body by controlling the concentration of the sulfuric acid, the addition amount of the water, the reaction temperature and the stirring and grinding strength;

s3, adding water to make the first generated filterable silicon coagulation body and the incompletely reacted lump material react for the second time to generate filterable silicon coagulation body;

s4, adding a cosolvent to improve the ionic strength of the system and strengthen the coagulation behavior of the soluble silicon, then diluting to a set solid-liquid ratio, and carrying out solid-liquid separation;

the hydrated oxide slag comprises oxyhydroxide and hydroxide gel; the hydrated oxide slag is hydrated iron oxide aluminum slag;

in the step S1, dehydrating the hydrated oxide slag to reduce the water content to 5-70%;

the dehydrated slag is scattered and crushed to ensure that the particle diameter of the gel slag is less than or equal to 10 cm;

in S2, the total water content of the drying alteration process control system is less than or equal to 80%, and the concentration of sulfuric acid is 20-98%; the reaction temperature is 25-300 ℃; the stirring intensity standard is that the materials are prohibited from crusting into big balls or blocks, and the particle size of the materials is controlled to be less than or equal to 5 mm; the reaction time is 0.5 to 2 hours;

in the step S4, adding water until the solid-to-liquid ratio is set to be 1: 0.5-1: 4kg/L, and carrying out secondary reaction to generate a filterable silicon coagulation body;

in the S4, the cosolvent is added, and the total ionic strength of the system after reaction is ensured to be more than or equal to 10mol/L, and the ionic strength of the system after reaction is more than 15 mol/L; the cosolvent is a reducing agent or inorganic salt; the reaction time is 0.5 h-2 h; the reaction temperature is 25-90 ℃.

2. The method according to claim 1, wherein in S1, the hydrated oxide slag is dehydrated to reduce the moisture to 30 to 60%.

3. The method according to claim 2, wherein the hydrated oxide sludge is dehydrated using a thickener, a filter press or a drying device.

4. The method according to claim 1, wherein in the S2, the sulfuric acid concentration is 30% to 65%; the reaction temperature is 40-95 ℃.

5. The method according to claim 1, wherein in S4, water is added to a set solid-to-liquid ratio of 1:1 to 1:3 kg/L.

6. The method according to claim 1, wherein in the step S4, the reaction temperature is 35-70 ℃.

7. The method of claim 1, wherein the S2, the S3 and the S4 are continuously performed when the hydrated oxidized slag is free from physical inclusion weak contact and chemical wrapping.