阅读说明：本技术 从优溶渣中浸出有价资源的方法 (Method for leaching valuable resources from optimal slag ) 是由 王超 姜子奕 曾中贤 许昆 刘浩 尹亮 谭国强 李春湘 刘玲 曾健 洪穗 于 2020-12-21 设计创作，主要内容包括：本发明涉及一种从优溶渣中浸出有价资源的方法,包括如下步骤：1)向优溶渣中加入无机酸,并进行搅拌加热,得到浸出液；2)待所述浸出液升温至70-80℃时,加入硫脲,待煮沸后停止加热,继续搅拌陈化；3)待温度降至50-70℃时,加入絮凝剂,待搅拌至溶液中出现沉淀时,停止搅拌,自然沉降；4)通过过滤进行固液分离,得到滤液。本发明提供的从优溶渣中浸出有价资源的方法,通过无机酸、硫脲及絮凝剂的相互协同作用,可以提高有价资源的浸出率,并且还可以改善过滤效果,从而提高生产效率。(The invention relates to a method for leaching valuable resources from superior slag, which comprises the following steps: 1) adding inorganic acid into the optimal-dissolution slag, stirring and heating to obtain a leaching solution; 2) adding thiourea when the temperature of the leaching solution is raised to 70-80 ℃, stopping heating after the leaching solution is boiled, and continuing stirring and aging; 3) when the temperature is reduced to 50-70 ℃, adding a flocculating agent, stopping stirring when the solution is stirred until precipitation appears, and naturally settling; 4) solid-liquid separation is carried out by filtration to obtain filtrate. The method for leaching valuable resources from the excellent slag can improve the leaching rate of the valuable resources and the filtering effect through the mutual synergistic effect of the inorganic acid, the thiourea and the flocculating agent, thereby improving the production efficiency.)

1. A method for leaching valuable resources from excellent slag is characterized by comprising the following steps:

1) adding inorganic acid into the optimal-dissolution slag, stirring and heating to obtain a leaching solution;

2) adding thiourea when the temperature of the leaching solution is raised to 70-80 ℃, stopping heating after the leaching solution is boiled, and continuing stirring and aging;

3) when the temperature is reduced to 50-70 ℃, adding a flocculating agent, stopping stirring when the solution is stirred until precipitation appears, and naturally settling;

4) solid-liquid separation is carried out by filtration to obtain filtrate.

2. The method according to claim 1, wherein the mineral acid is selected from hydrochloric acid.

3. The method according to claim 1 or 2, wherein the liquid-solid ratio of the inorganic acid to the slag is (1.5-3): 1.

4. the method according to any one of claims 1 to 3, wherein the concentration of the inorganic acid at the time of the continued stirring aging is 1 to 3 mol/L.

5. The method according to claim 1, wherein the thiourea is present in an amount of 0.1-0.2% by mass of the leach solution.

6. The method according to claim 1, characterized in that the flocculant is polyacrylamide, and the mass fraction of the polyacrylamide is 0.1-0.3%.

7. A process according to claim 6, wherein the polyacrylamide is added in an amount of from 0.2 to 0.5% by volume of the leach solution.

8. The process according to claim 1, characterized in that the aging time is comprised between 3 and 6 h.

9. The method according to claim 1, wherein the slag includes the following components in parts by mass:

U₃O₈，0.1％-3％；

ThO₂，5-20％；

3-10% of cerium oxide in rare earth;

the balance being impurities.

10. The method according to claim 1, wherein the filtration is performed by a filter press to obtain the filtrate, and the filtration time is 4-8 h.

Technical Field

The invention relates to the technical field of optimal slag treatment, in particular to a method for leaching valuable resources from optimal slag.

Background

The optimal dissolving slag is waste slag generated after rare earth products are obtained by adding alkali into monazite concentrate for decomposition and leaching, the waste slag still contains a large amount of valuable resources such as uranium, thorium, rare earth and the like, and the uranium and the thorium are radioactive elements, so that the environment can be polluted and the human health can be harmed if the waste slag is directly discharged into the environment. In addition, a large amount of rare earth in the waste slag is wasted, so that valuable resources in the leaching excellent dissolving slag have important significance.

At present, valuable resources such as uranium, thorium and the like are leached out by leaching the excellent slag mainly through acid and then carrying out solid-liquid separation through an organic solvent, however, in the method, the leaching rate of the valuable resources is low, and the subsequent filtration is very difficult, so that the production efficiency is reduced.

Therefore, in the process of leaching out valuable resources of the high-quality slag, the research and development of a leaching method with high leaching rate and easy filtration are urgently needed.

Disclosure of Invention

The invention aims to provide a method for leaching valuable resources from high-quality slag, and aims to solve the problems of low leaching rate and difficult filtration of the valuable resources in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a method for leaching valuable resources from superior slag, which comprises the following steps:

1) adding inorganic acid into the optimal-dissolution slag, stirring and heating to obtain a leaching solution;

2) adding thiourea when the temperature of the leaching solution is raised to 70-80 ℃, stopping heating after the leaching solution is boiled, and continuing stirring and aging;

3) when the temperature is reduced to 50-70 ℃, adding a flocculating agent, stopping stirring when the solution is stirred until precipitation appears, and naturally settling;

4) solid-liquid separation is carried out by filtration to obtain filtrate.

In some embodiments of the invention, the mineral acid is selected from hydrochloric acid.

In some embodiments of the invention, the liquid-to-solid ratio of the inorganic acid to the slag is (1.5-3): 1.

in some embodiments of the invention, the concentration of the inorganic acid is 1 to 3mol/L during the continued stirring and aging.

In some embodiments of the invention, the thiourea is present in an amount of 0.1-0.2% by mass of the leach solution.

In some embodiments of the invention, the flocculant is polyacrylamide, and the mass fraction of the polyacrylamide is 0.1-0.3%.

In some embodiments of the invention, the polyacrylamide is added in an amount of 0.2 to 0.5% by volume of the leachate.

In some embodiments of the invention, the aging time is from 3 to 6 hours.

In some embodiments of the present invention, the slag flux comprises the following components in parts by mass:

U₃O₈，0.1％-3％；

ThO₂，5-20％；

3-10% of cerium oxide in rare earth;

the balance being impurities.

In some embodiments of the invention, the time for natural settling is 30-60 min.

In some embodiments of the invention, the filtration is by a filter press to obtain the filtrate, and the filtration time is from 4 to 8 hours.

The embodiment provided by the invention has at least the following beneficial effects:

the method for leaching valuable resources from the excellent slag can improve the leaching rate of the valuable resources and the filtering effect through the mutual synergistic effect of the inorganic acid, the thiourea and the flocculating agent, thereby improving the production efficiency. In addition, the method is simple to operate, safe, reliable, free of environmental pollution and suitable for industrial production.

In addition to the technical problems solved by the present invention, the technical features constituting the technical solutions, and the advantages brought by the technical features of the technical solutions, described above, other technical problems solved by the method for leaching valuable resources from fine smelting slag provided by the present invention, other technical features included in the technical solutions, and advantages brought by the technical features will be further explained in detail in the detailed description.

Detailed Description

The technical solutions in the examples of the present disclosure will be clearly and completely described below in connection with the specific embodiments of the present disclosure, and it is obvious that the described embodiments and/or examples are only a part of the embodiments and/or examples of the present disclosure, and not all embodiments and/or examples. All other embodiments and/or all other examples that can be obtained by one of ordinary skill in the art without making any inventive step based on the embodiments and/or examples in the present disclosure are within the scope of the present disclosure.

In the description of the present specification, the term "comprising", "including" or "containing" means that it may have, in addition to the components, other components which impart different properties to the heavy metal stabilizing chelating agent. In addition, the terms "comprising," including, "or" containing "as used in this disclosure may also include" consisting essentially of, and may instead be "or" consisting of.

In the description of the present specification, amounts, ratios, and the like are by weight unless otherwise specified.

In the description of the present specification, reference to the description of the terms "one embodiment", "some embodiments", "an illustrative embodiment", "an example", "a specific example", or "some examples", etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The invention provides a method for leaching valuable resources from superior slag, which comprises the following steps:

1) adding inorganic acid into the optimal-dissolution slag, stirring and heating to obtain a leaching solution;

2) adding thiourea when the temperature of the leaching solution is raised to 70-80 ℃, stopping heating after the leaching solution is boiled, and continuing stirring and aging;

3) when the temperature is reduced to 50-70 ℃, adding a flocculating agent, stopping stirring when the solution is stirred until precipitation appears, and naturally settling;

4) solid-liquid separation is carried out by filtration to obtain filtrate.

As mentioned above, the preferential dissolution slag is subjected to acid leaching of valuable resources (such as uranium, thorium, rare earth and the like), the leaching rate is improved by stirring and heating, thiourea can be added when the temperature is raised to 70-80 ℃, compared with the prior art in which hydrogen peroxide is added, the leaching reaction temperature is higher, and simultaneously, the hydrogen peroxide is volatile, so that a large amount of hydrogen peroxide is lost, and hydrogen peroxide needs to be supplemented in the reaction process, thereby increasing the safety risk and the leaching cost. Moreover, hydrogen peroxide also inhibits flocculation of the flocculant, resulting in poor filtration performance. The addition of thiourea can not only prevent Ce in the leaching solution³⁺Is oxidized into Ce⁴⁺And the flocculation effect of the subsequent flocculating agent is not influenced, so that the filtering performance of the leaching solution is improved, and the leaching rate of valuable resources is improved.In addition, thiourea is added at a proper temperature, which is beneficial to improving the leaching rate of valuable resources and is also beneficial to the conversion of cerium, namely tetravalent cerium which is not dissolved in acid is converted into trivalent cerium which is dissolved in acid, so that the leaching rate of rare earth is improved. Above or below the above temperature range, leaching of valuable resources may be adversely affected. After thiourea is added, the temperature is continuously increased to boiling, so that the titanium compound in the slag can be further hydrolyzed, and the silicon compound can form polymer precipitate, thereby avoiding the leaching solution containing impurities such as titanium, silicon and the like to influence the leaching of valuable resources. Meanwhile, the subsequent solid-liquid separation is improved. And (3) after the temperature is reduced to 50-70 ℃, adding a flocculating agent to polymerize the particles which are not dissolved in the acid, and separating the aggregated particles from the solution through subsequent filtration to obtain a filtrate containing valuable resources. If the temperature is higher or lower than 50-70 ℃, the flocculation effect and the subsequent solid-liquid separation are affected.

In some embodiments of the present invention, the inorganic acid may be at least one selected from hydrochloric acid, sulfuric acid, and nitric acid.

In some embodiments of the invention, the inorganic acid is hydrochloric acid, the hydrochloric acid reacts with rare earth in the slag to form rare earth chloride, and the rare earth chloride obtained by the invention can be directly used as a single rare earth compound, a petroleum cracking catalyst, a polishing powder raw material and a raw material of each component rare earth enrichment without transformation treatment of rare earth salt, so that the inorganic acid is widely applied to the fields of chemical industry, light textile and agriculture. The initial concentration of the hydrochloric acid is generally selected to be about 6mol/L, so that the residual acid concentration and leaching rate of the optimal slag can be ensured when the optimal slag is completely leached, and the acid concentration of the extraction stock solution can be ensured when the uranium, the thorium and the rare earth are extracted and separated subsequently.

As the reaction proceeds, the hydrochloric acid is gradually consumed, and the concentration of the hydrochloric acid is gradually reduced, but in order to facilitate the subsequent filtration and leaching of valuable resources, the concentration of the hydrochloric acid is controlled to be 1-3mol/L during aging. Illustratively, the concentration of the hydrochloric acid can be, but is not limited to, 1mol/L, 2mol/L and 3mol/L, and the concentration of the acid left in the leachate can be appropriately adjusted in order to ensure the concentration of the acid in the extraction stock solution during the extraction and separation of the uranium, the thorium and the rare earth in the actual leaching process.

As mentioned above, in the prior art, the leaching reaction temperature is relatively high, and meanwhile, the hydrogen peroxide is volatile, so that a large amount of hydrogen peroxide is lost, and chlorine formed by hydrochloric acid is released from the leaching solution, so that the environment is polluted, and the safety of operators is threatened. The addition of thiourea can inhibit the generation of chlorine, as shown in formula I), thereby avoiding the environment from being polluted and reducing the safety threat to operators.

8CeO₂+26HCl+(H₂N)₂CS＝8CeCl₃+2NH₄Cl+10H₂O+H₂SO₄+CO₂↑Ⅰ)

Further, the addition of the inorganic acid can leach valuable resources in the high-quality slag, the addition amount of the inorganic acid also affects the leaching rate and the filtering performance of the valuable resources, and when the valuable resources in the filtrate are separated and form solids, the filtrate needs to be heated at a high temperature. If the addition amount of the inorganic acid is too large, the energy consumption is too high, and the leaching cost is increased. Therefore, the liquid-solid ratio of the inorganic acid to the monazite optimum slag can be (1.5-3) by comprehensively considering the leaching rate, the filtering performance and the leaching cost of valuable resources: 1. for example, the ratio of inorganic acid to monazite slag may be, but is not limited to, 1.5: 1. 2.0: 1. 2.5: 1. 3.0: 1, the specific liquid-solid ratio can be adjusted according to actual production.

In this embodiment, the addition amount of thiourea is not particularly limited, and may be appropriately configured according to the quality of the leaching solution. In some embodiments of the invention, the mass of thiourea is 0.1-0.2% of the mass of the leach solution, e.g. 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%. The addition amount of thiourea in the range can obviously improve the conversion rate of cerium, and can enable the conversion rate of cerium to reach more than 92 percent. Besides, the leaching rate of uranium and thorium can reach more than 95%, and the leaching rate of rare earth can reach more than 92%.

In some embodiments of the invention, the aging time is generally from 3 to 6 hours. Illustratively, the aging time may be, but is not limited to, 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h, 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h, 5.0 h.

In the embodiment provided by the present invention, there is no particular limitation on the type of the flocculant, and the flocculant may be one or both of an inorganic flocculant and an organic flocculant. For example, the inorganic flocculant may be, but is not limited to, iron-based metal salt, aluminum-based metal salt, inorganic polymeric flocculant (PAL, PAS, PAP, PFS, PFC, PFP, PS), etc., and the organic flocculant may be, but is not limited to, polyacrylamide, polydimethyl diallyl ammonium chloride, complex coagulant, etc.

In some embodiments of the invention, the flocculating agent is selected to be polyacrylamide, wherein the polyacrylamide is anionic polyacrylamide which will cause non-ionic adsorption or cross-linking of fine particles in the leach suspension.

Further, in some embodiments of the present invention, the mass fraction of polyacrylamide is 0.1 to 0.3%.

Furthermore, in some embodiments of the present invention, the polyacrylamide is added in an amount of 0.2-0.5% by volume of the leachate, so that the filtering performance of the leachate can be further improved, and the leaching rate of valuable resources can be increased.

In some embodiments of the invention, the preferential slag comprises the following ingredients: u shape₃O₈、ThO₂Rare earth and other impurities. Wherein, calculated by mass fraction, U₃O₈The mass fraction of (a) is 0.1% to 3%, specifically, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.32%, 0.34%, 0.36%, 0.38%, 0.40%, 0.42%, 0.44%, 0.46%, 0.48%, 0.50% or 0.51% to 1.0% or 1.1% to 2.0% or 2.1% to 3.0%; ThO₂The content of (B) is 5-20%, specifically 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8.0%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9.0%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10.0%, 10.1%, 10.2%, 10.3%, 10.4%, 10.5%, 10.6%, 10.7%, 10.8%, 10.9%, 11.0%, 11.1%, 13.12%, 13.1%, 13.6%, 13.7%, 13.8%, 13.9.9.9%, 12.9.9%, 12.9%, 12.1%, 12%, 12.1%, 13.1%, 12%, 12.6%, 13.1%, 13.6%, 13.1%, 12% or 13.6%, 13.7%, 13.1% or 13% of the composition -19% or 19.1% -20%; a mass fraction of cerium oxide in the rare earth is 3-10%, specifically, may be 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7.8%, 7.9%, 8.0%, 8.9%, 8%, 8.9%, 8%, 8.9%, 8%, 8.9%, 8%, 8.9% of 3.; the balance being impurities such as titanium and silicon.

In some embodiments of the invention, the stirring time after adding the flocculating agent can be 30s, 45s, 60s, 90s and 120s, and the specific stirring time can be determined according to the flocculation effect observed in actual production.

In some embodiments of the invention, the filtrate is obtained by natural settling for 30-60min and then filtering.

In some embodiments of the invention, the leachate is separated by filtration through a box filter press to obtain a filtrate containing uranium, thorium and rare earth, and the filter cake is washed and filtered by pulping and then can be buried or temporarily stored in a warehouse. Compared with the filtering period of more than 18h in the prior art, the method provided by the invention can shorten the filtering period to 4-8 h.

In conclusion, the method for leaching valuable resources from the high-quality slag provided by the invention can improve the leaching rate of valuable resources and the filtering effect through the mutual synergistic action of the inorganic acid, the thiourea and the flocculant, thereby improving the production efficiency. In addition, the method is simple to operate, safe, reliable, free of environmental pollution and suitable for industrial production.

The method for leaching valuable resources from the fine slag of the present invention will be described in detail below with reference to specific examples.

Unless otherwise specified, the chemical materials and instruments used in the following examples are all conventional chemical materials and conventional instruments, and are commercially available.

Example 1

The embodiment provides a method for leaching valuable resources from an excellent slag, which comprises the following steps:

1) adding 2200L5.9mol/LHCl hydrochloric acid solution into an optimal slag leaching tank, starting a stirring and heating control system, and adding 1.987t of single optimal slag (U)₃O₈：0.46％、ThO₂:12.4％、CeO₂5.3 percent), controlling the reaction temperature to be 60 ℃ and the reaction time to be 1h to obtain a leaching solution;

2) and when the leaching reaction temperature rises to 71 ℃, adding 4.5kg of thiourea into the leaching solution, continuously stirring and heating until the leaching solution is boiled for 30min, stopping heating, and stirring and aging for 4.0 h.

3) After the temperature is reduced to 50 ℃, adding 7.0L of 0.1 percent polyacrylamide solution, stirring for 45s, stopping stirring, and naturally standing for settling for 35 min;

4) transferring the supernatant overflow slurry and the underflow slurry into a box type filter press for filtering and separating to respectively obtain filtered supernatant and filter cakes. Wherein the filtering area is 60m²The filtration cycle of the membrane filter pressThe time is 3.5 h.

Detecting and analyzing, filtering U, ThO in the clear liquid₂、CeO₂Content of Ce and filter cake₂O₃The leaching rates of uranium, thorium and rare earth are respectively as follows according to the leaching solution: eta_U：98.21％，η_Th：97.63％，η_Ce: 93.84 percent and the conversion rate of cerium is 93.31 percent according to the leached residues.

Example 2

The embodiment provides a method for leaching valuable resources from an excellent slag, which comprises the following steps:

1) adding 1900L6.2mol/LHCl hydrochloric acid solution into the optimal solution slag leaching tank, starting a stirring and heating control system, and adding 1.211t of optimal solution slag (U)₃O₈：0.81％、ThO₂:9.8％、CeO₂4.8 percent), controlling the reaction temperature to be 55 ℃ and the reaction time to be 1.5 hours to obtain a leaching solution;

2) and when the leaching reaction temperature is increased to 73 ℃, adding 3.9kg of thiourea into the leaching solution, continuously stirring and heating until the leaching solution is boiled for 30min, stopping heating, and stirring and aging for 4.5 h.

3) After the temperature is reduced to 55 ℃, adding 7.3L of 0.1 percent polyacrylamide solution, stirring for 60s, stopping stirring, and naturally standing for 40 min;

4) transferring the supernatant overflow slurry and the underflow slurry into a box type filter press for filtering and separating to respectively obtain filtered supernatant and filter cakes. Wherein the filtering area is 60m²The filtration cycle time of the membrane filter press of (1) was 3.0 h.

Detecting and analyzing, filtering U, ThO in the clear liquid₂、CeO₂Content of Ce and filter cake₂O₃The leaching rates of uranium, thorium and rare earth are respectively as follows according to the leaching solution: eta_U：97.74％，η_Th：97.01％，η_Ce: 93.29 percent, and the conversion rate of cerium calculated by leaching residues is 93.09 percent.

Example 3:

the embodiment provides a method for leaching valuable resources from an excellent slag, which comprises the following steps:

1) will be provided with2400L6.1mol/LHCl hydrochloric acid solution is added into an optimal slag leaching tank, a stirring and heating control system is started, and 1.306t optimal slag (U) is added₃O₈：0.61％、ThO₂:13.7％、CeO₂6.2 percent), controlling the reaction temperature to be 60 ℃ and the reaction time to be 1.5 hours to obtain a leaching solution;

2) and when the leaching reaction temperature is raised to 70 ℃, adding 4.7kg of thiourea into the leaching solution, continuously stirring and heating until the leaching solution is boiled for 31min, stopping heating, and stirring and aging for 3.5 h.

3) After the temperature is reduced to 60 ℃, adding 8.1L of 0.1 percent polyacrylamide solution, stirring for 60s, stopping stirring, and naturally standing for settling for 40 min;

4) transferring the supernatant overflow slurry and the underflow slurry into a box type filter press for filtering and separating to respectively obtain filtered supernatant and filter cakes. Wherein the filtering area is 60m²The filtration cycle time of the membrane filter press of (1) was 3.0 h.

Detecting and analyzing, filtering U, ThO in the clear liquid₂、CeO₂Content of Ce and filter cake₂O₃The leaching rates of uranium, thorium and rare earth are respectively as follows according to the leaching solution: eta_U：96.12％、η_Th：96.98％、η_Ce: 94.85 percent, and the conversion rate of cerium calculated by leaching slag is alpha: 94.71 percent.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.