Method for neutralizing, precipitating and removing impurities from rare earth leaching solution of weathering crust elution-deposited rare earth ore

Abstract

The invention relates to the technical field of hydrometallurgy, in particular to a method for neutralizing, precipitating and removing impurities from a rare earth leaching solution of weathering crust eluviation type rare earth ore and application. The method is characterized by comprising the following steps: slowly adding a precipitator into the rare earth leaching solution of the weathering crust elution-deposited rare earth ore until the pH value is 5-6, and carrying out solid-liquid separation to obtain an aluminum-containing precipitate and aluminum-removed rare earth feed liquid after the stirring reaction is completed. Compared with an existing method, the method has the advantages that the impurity removal rate is higher, the rare earth loss rate is lower, and sediment sedimentation is faster. And the precipitant is easy to obtain and store, green and environment-friendly, low in cost and simple in precipitation process, and has a relatively good application value.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for neutralizing, precipitating and removing impurities from rare earth leaching liquid of weathering crust elution type rare earth ore. Background Art

[0002] Weathering crust elution type rare earth ore, also known as ion adsorption type rare earth ore, is a kind of medium and heavy rare earth-rich ore that was first discovered and industrially utilized in my country. It is mainly distributed in eight provinces in southern my country. Rare earths are adsorbed on clay minerals in the form of hydrated ions or hydroxyl hydrated ions and can be enriched by ion exchange. When electrolyte solution is added to the original ore, non-rare earth ions such as aluminum, calcium, magnesium and iron adsorbed on clay minerals in the ionic phase will also enter the leachate along with the rare earth ions. For the ore body with more complete weathering or thicker weathering layer, the more clay minerals it contains, the more impurity ions it adsorbs, and the more impurity ions enter the leachate with the rare earth leaching. Aluminum ions are the main impurities in the leaching process of weathering crust elution type rare earth ore. Its presence in the leachate will have a serious impact on the subsequent enrichment of rare earths. When the rare earths in the leachate are extracted by solvent extraction, aluminum ions will emulsify the extraction system under certain conditions; when oxalic acid is used as a precipitant to enrich the rare earths in the leachate, aluminum ions will form soluble complexes with oxalate ions, which will increase the amount of oxalic acid used and reduce the yield of rare earth precipitation; when carbonates or bicarbonates are used as precipitants to enrich the rare earths in the leachate, aluminum will form co-precipitates with the rare earths, seriously reducing the quality of the rare earth products. At the same time, the presence of aluminum will also lead to increased consumption of rare earth precipitants, poor crystallinity of precipitation products, and difficulty in washing and filtering precipitation, which brings great difficulties to the rare earth precipitation process. Therefore, before precipitation and recovery of rare earths, the rare earth leachate must be treated to remove impurities.

[0003] At present, ammonium bicarbonate is used in industry to remove impurities from rare earth leaching solution. This method uses the difference in pH value when aluminum hydroxide and rare earth hydroxide are precipitated, and separates aluminum ions and rare earth ions by accurately controlling the pH value of the solution. However, this process causes more than 8% rare earth loss and brings ammonia nitrogen pollution. In order to solve the ammonia nitrogen problem, scientific researchers have conducted a lot of research on related ammonium-free precipitants, including the use of alkaline reagents such as CaO, MgO, and NaOH for neutralization and impurity removal. However, the alkaline precipitant impurity removal process not only has the problem of large rare earth loss, but also introduces new impurities. Therefore, although the current process can remove most of the aluminum, the separation efficiency of rare earth and aluminum is low, the aluminum removal process leads to large rare earth loss, and serious waste of rare earth resources. Therefore, finding an efficient and green rare earth impurity remover is of great significance for the effective and comprehensive utilization of rare earth resources and the protection of the ecological environment. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned shortcomings of existing precipitants, utilize the different precipitation pH characteristics of impurity ions and rare earth ions, and propose a method for neutralizing and precipitating impurities in rare earth leachate of weathering crust elution type rare earth ore. The method has a high aluminum removal rate, low rare earth loss, low equipment requirements, simple operation, and no pollution.

[0005] The invention discloses a method for neutralizing, precipitating and removing impurities from rare earth leaching solution of weathering crust elution type rare earth ore, which is characterized in that a precipitant is slowly added to the rare earth leaching solution of weathering crust elution type rare earth ore until the pH value is 5-6, and after the stirring reaction is completed, solid-liquid separation is performed to obtain an aluminum-containing precipitate and a rare earth liquid after aluminum removal.

[0006] The precipitant is an aqueous solution composed of one or more of histidine, lysine and arginine.

[0007] Furthermore, the precipitant is 0.1wt%-6wt%.

[0008] Furthermore, the stirring reaction time is 5 min to 20 min.

[0009] Furthermore, the stirring reaction temperature is 0°C to 80°C.

[0010] Furthermore, solid-liquid separation is performed after standing for 5 to 20 minutes.

[0011] Furthermore, in the rare earth leaching solution of the weathering crust elution type rare earth ore, the rare earth ion concentration is 1g / L to 20g / L in terms of RE.

[0012] Furthermore, in the rare earth leaching solution of the weathering crust elution type rare earth ore, the aluminum ion concentration is 0.01g / L to 2g / L.

[0013] Furthermore, the amount of the precipitant used is 100% to 150% of the theoretical amount used for reaction with aluminum.

[0014] Furthermore, the rare earth leaching solution of the weathering crust elution type rare earth ore is prepared by column leaching method / stirring method using an inorganic leaching agent as the leaching agent of the weathering crust elution type rare earth ore.

[0015] Furthermore, the inorganic leaching agent is one or more combinations of ammonium sulfate, ammonium chloride, magnesium sulfate, magnesium chloride and magnesium nitrate.

[0016] The present invention uses a precipitant to treat a rare earth solution containing a large amount of aluminum ions, thereby achieving the removal of aluminum ions from the rare earth solution, ensuring that the aluminum ion removal rate reaches 100%, and the rare earth loss rate does not exceed 4%. The aluminum ions in the rare earth solution are removed while the rare earth ion loss rate is greatly reduced.

[0017] The present invention directly adds a precipitant under stirring, adjusts the pH value of the solution to a certain value, and then filters the precipitate to achieve separation, which not only greatly reduces the rare earth loss rate, but also has low equipment requirements, does not require a large amount of plant area, reduces production costs, and is easy to operate. The generated precipitate has a larger particle size and is easier to settle. It provides an extremely effective and economical way to remove aluminum from a rare earth solution.

[0018] When the method of the present invention is used for precipitation, only a precipitant needs to be added without introducing other impurities, which simplifies the process flow and can also reduce the amount of wastewater and waste residue to be treated. It has the advantages of being environmentally friendly in operation, environmentally friendly in production process, and clean in metallurgical process. DETAILED DESCRIPTION

[0019] The following is a specific embodiment of the present invention, which further describes the features and performance of the technical solution of the present invention in detail. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0020] Example 1

[0021] The present embodiment provides a precipitant for neutralizing and precipitating rare earth liquid and removing impurities, which is an aqueous solution composed of histidine. The mass percentage content of histidine is 0.5%. The rare earth liquid is prepared by stirring and leaching a weathering crust elution type rare earth ore with 2% NS, and the rare earth ion concentration in the rare earth liquid is 20g / L and the aluminum ion concentration is 2g / L. When the pH of the solution is adjusted to 5.5, the rare earth ion loss rate is 3.77% and the aluminum ion removal rate is 100%.

[0022] Example 2

[0023] The implementation method is the same as that of Example 1, except that the precipitant is a solution containing 1% histidine and 1% arginine by mass percentage. The rare earth solution is prepared by column leaching of weathering crust elution type rare earth ore by 1% MS, 1% MC, and 1% MN, and the rare earth ion concentration in the rare earth solution is 5g / L and the aluminum ion concentration is 1g / L. When the solution pH is adjusted to 5.6, the rare earth ion loss rate is 3.96% and the aluminum ion removal rate is 100%.

[0024] Example 3

[0025] The implementation method is the same as that of Example 1, except that the precipitant contains 0.4% histidine and 0.2% lysine by mass percentage, and the rare earth liquid is prepared by stirring and leaching 1% NC and 1% MS from a weathering crust elution type rare earth ore, and the rare earth ion concentration in the rare earth liquid is 2 g / L and the aluminum ion concentration is 2 g / L. When the solution pH is adjusted to 5.4, the rare earth ion loss rate is 3.38% and the aluminum ion removal rate is 100%.

[0026] Example 4

[0027] The implementation method is the same as that of Example 1, except that the precipitant contains 0.2% histidine, 0.2% lysine, and 0.2% arginine by mass percentage, and the rare earth liquid is prepared by column leaching of 1% NC, 1% MC, and 1% MN from a weathering crust elution type rare earth ore, and the rare earth ion concentration in the rare earth liquid is 5 g / L and the aluminum ion concentration is 0.01 g / L. When the solution pH is adjusted to 5.5, the rare earth ion loss rate is 3.55% and the aluminum ion removal rate is 100%.

[0028] Comparative Example 1

[0029] The implementation method is the same as that of Example 1, except that the precipitant is a 1% by mass ammonium bicarbonate solution. The rare earth solution is prepared by leaching a weathering crust elution type rare earth ore through a 2% NS column, and the rare earth ion concentration in the rare earth solution is 20 g / L and the aluminum ion concentration is 2 g / L. When the solution pH is adjusted to 5.6, the rare earth ion loss rate is 10.88% and the aluminum ion removal rate is 97.72%.

[0030] Comparative Example 2

[0031] The implementation method is the same as that of Example 1, except that the precipitant is a solution of 1% CaO and 1% MgO by mass percentage. The rare earth liquid is prepared by stirring and leaching 1% MS, 1% MC, and 1% MN from a weathering crust elution type rare earth ore. The rare earth ion concentration in the rare earth liquid is 5 g / L and the aluminum ion concentration is 1 g / L. When the solution pH is adjusted to 5.2, the rare earth ion loss rate is 6.39% and the aluminum ion removal rate is 89.49%.

[0032] For matters not mentioned above, the prior art applies.

[0033] The above embodiments are only for describing and illustrating specific embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, any modification, equivalent substitution, improvement, etc. made to the technical solution of the present invention by ordinary engineering technicians in the field shall be included in the protection scope determined by the claims of the present invention.

Claims

1. A method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore, characterized in that: Slowly adding a precipitant to the rare earth leaching solution of the weathering crust elution type rare earth ore until the pH value is 5 to 6, stirring and reacting, and performing solid-liquid separation to obtain an aluminum-containing precipitate and a rare earth leaching solution of the weathering crust elution type rare earth ore after aluminum removal; The precipitant is an aqueous solution composed of one or more of histidine, lysine and arginine.

2. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: The precipitant is 0.1wt%-6wt%.

3. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: The stirring reaction time is 5 min to 20 min.

4. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: The temperature of the stirring reaction is 0°C to 80°C.

5. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: After standing for 5 to 20 minutes, solid-liquid separation is performed.

6. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: In the rare earth leaching solution of weathering crust elution type rare earth ore, the rare earth ion concentration is 1g / L~20g / L, calculated as RE.

7. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: The aluminum ion concentration in the rare earth leaching solution of weathering crust elution type rare earth ore is 0.01g / L~2g / L.

8. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: The amount of the precipitant used is 100% to 150% of the theoretical amount used for reaction with aluminum.

9. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 1, characterized in that: The rare earth leaching solution of the weathering crust elution type rare earth ore adopts an inorganic leaching agent as the leaching agent of the weathering crust elution type rare earth ore and is prepared by a column leaching method / stirring method.

10. The method for neutralizing and precipitating impurities from rare earth leaching solution of weathering crust elution type rare earth ore according to claim 9, characterized in that: The inorganic leaching agent is one or more combinations of ammonium sulfate, ammonium chloride, magnesium sulfate, magnesium chloride and magnesium nitrate.