Method for saponifying and organically extracting and separating mixed rare earth chloride feed liquid by using lanthanum oxide

Abstract

The invention discloses a method for saponifying and organically extracting and separating mixed rare earth chloride feed liquid by using lanthanum oxide, and belongs to the technical field of rare earth extraction and separation. Comprising the following steps: firstly, saponifying a blank organic matter by using solid lanthanum oxide powder, allowing the saponified La < 3 + >-loaded organic matter to stand for clarification, and then feeding the clarified organic matter into an extraction line for directly extracting and separating a mixed rare earth chloride feed liquid. The lanthanum chloride liquid produced through extraction and separation enters a rear-end precipitation process and then is subjected to a precipitation reaction with ammonium bicarbonate or a mixed precipitator of ammonium bicarbonate and ammonia water to generate lanthanum carbonate, then the lanthanum carbonate is placed in a natural gas kiln to be calcined, and lanthanum oxide is produced. The saponification is pure, the saponification reaction is fast, the emission of saponification wastewater is less, the lanthanum oxide solid powder is used for saponifying the organic matter, only a trace amount of saponification wastewater is generated, the saponification wastewater does not contain inorganic salt substances, wastewater treatment is not needed, and the wastewater treatment cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth extraction and separation, in particular to a method for separating mixed rare earth chloride solution by organic extraction using lanthanum oxide saponification. Background Art

[0002] At present, the extractant used for rare earth extraction and separation is mainly P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester), which belongs to the acidic phosphate extractant. This type of extractant has a certain extraction ability only after saponification reaction with alkaline substances. Therefore, in industry, alkaline substances such as magnesium bicarbonate solution, sodium hydroxide solution or ammonia water are often used as saponifiers and extractants. The saponified extractant combines with the rare earth ions in the feed liquid as an organic phase to form a complex, and the separation between the rare earth ions is achieved according to the difference in the stability of the formed complex. Then, the rare earth ions are extracted from the organic phase to the aqueous phase through a stripping agent such as hydrochloric acid to form various rare earth chloride products for the back-end precipitation process, and the extractant is recycled. When using magnesium bicarbonate solution, sodium hydroxide solution or ammonia water saponification extractant, saponification wastewater will be generated. The main components of the saponification wastewater are magnesium chloride, sodium chloride or ammonium chloride, and it also contains trace amounts of oil substances and other non-rare earth impurity ions. The composition is relatively complex and needs to be treated by pyrolysis or concentrated evaporation. The cost of treatment is relatively high. At the same time, since the saponifiers used in industry have low purity and contain more impurities, these impurity ions will be loaded into the organic matter after saponification, and will enter the extraction line along with the saponified organic matter, and eventually enter the extracted product, affecting the quality of the extracted product.

[0003] In summary, the following disadvantages of the prior art are as follows: 1. Large amount of saponification wastewater is discharged and the treatment cost is high: Since the existing conventional organic saponifiers mainly include magnesium bicarbonate solution, sodium hydroxide solution or ammonia water, etc., these saponifiers are all solutions, so a large amount of saponification wastewater will be generated after saponification of blank organic. Taking magnesium bicarbonate as an example, the concentration of magnesium bicarbonate solution prepared industrially is 7g / L (in terms of magnesium oxide), then the saponification of 1m 3 The saponification wastewater produced by blank organic matter is about 1.5m 3 Taking sodium hydroxide solution as an example, the concentration of sodium hydroxide solution used in industry is 5 mol / L, then the saponification of 1m 3 The saponification wastewater produced by blank organic matter is about 0.12m 3 Taking ammonia water as an example, the concentration of ammonia water used in industry is about 6.5 mol / L, so the saponification of 1m 3 The saponification wastewater produced by blank organic matter is about 0.1m 3The wastewater generated after the above conventional saponifiers saponify the organic matter is all high-salt wastewater. The magnesium chloride wastewater is generated after the blank organic matter is saponified with magnesium bicarbonate solution. The sodium chloride wastewater is generated after the blank organic matter is saponified with sodium hydroxide solution. The ammonium chloride wastewater is generated after the blank organic matter is saponified with ammonia water. These wastewaters cannot be reused in the rare earth smelting system and can only be treated by concentration and evaporation, and the cost of wastewater treatment is high.

[0004] 2. The saponified organic is not pure, which affects the quality of the extracted product: After the organic is saponified with magnesium bicarbonate solution, sodium hydroxide solution and ammonia water, the organic is loaded with magnesium ions, sodium ions and ammonium ions. After the saponified organic enters the extraction line, in order to increase the extraction amount and prevent the low-valent magnesium ions, sodium ions and ammonium ions from entering the extraction line, a rare earth soap section will be set at the front end of the extraction line. The raffinate is used as the soap material to exchange ions with the saponified organic, and the magnesium ions, sodium ions and ammonium ions in the saponified organic are replaced with rare earth ions in the raffinate outlet. The organic loaded with rare earth ions enters the extraction line for extraction and separation. The setting of the rare earth soap section will produce another part of wastewater, namely rare earth soap wastewater. This part of wastewater is generally mixed with the saponified wastewater and treated uniformly, which further increases the discharge of wastewater in the saponification stage of rare earth extraction. In addition, due to the extraction reaction of the rare earth soap extraction box and the clarification of the organic phase and the aqueous phase, the organic matter loaded with rare earth ions entering the extraction line may carry impurity ions into the extraction line, resulting in the separation of the organic phase and the aqueous phase in the rear extraction line and the purity of the raffinate product being affected. Figure 3 shown. Summary of the invention

[0005] The purpose of the present invention is to provide a method for using lanthanum oxide saponification organic extraction to separate mixed rare earth chloride liquid, which uses lanthanum oxide solid powder as a saponifier and extractant, and the saponified lanthanum soap organic directly enters the extraction line for extraction and separation. Since lanthanum oxide has strong alkalinity and high purity, when using lanthanum oxide solid powder to saponify organic, the saponification reaction is fast, the wastewater generated by saponification is small, and the impurity ions loaded by the lanthanum soap organic after saponification are small. After the lanthanum soap organic enters the extraction line, with the exchange of rare earth ions, the La loaded in the organic is 3+ The lanthanum chloride solution is then exchanged into the aqueous phase to produce a lanthanum chloride solution, which then enters a precipitation and calcination process to obtain lanthanum oxide. A small amount of lanthanum oxide is recycled as a saponifier, and a large amount of lanthanum oxide is sold as a product. The present invention reduces the discharge of saponification wastewater, improves the purity of saponified organic matter, and optimizes the rare earth extraction and separation process.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The method for separating a mixed rare earth chloride solution by organic extraction using lanthanum oxide saponification comprises the following steps:

[0008] Step 1: Use solid lanthanum oxide powder to saponify blank organic matter. The addition ratio of solid lanthanum oxide powder and blank organic matter is 1m 3 Add 30kg lanthanum oxide to the blank organic; the saponification reaction time is more than 30min, the saponification reaction temperature is 40-60℃, and the organic saponification value is controlled to be 0.5mol / L;

[0009] Step 2: Load La after saponification in step 1 3+ The lanthanum soap organic solution enters the extraction line after being clarified by standing, and is directly used for extraction and separation of mixed rare earth chloride liquid;

[0010] Step 3: The lanthanum chloride liquid produced by extraction and separation enters the back-end precipitation process, and undergoes precipitation reaction with ammonium bicarbonate or a mixed precipitant of ammonium bicarbonate and ammonia water to produce lanthanum carbonate, and then the produced lanthanum carbonate is calcined in a natural gas kiln to produce lanthanum oxide;

[0011] Step 4: A small portion of the produced lanthanum oxide is used to saponify blank organic matter to achieve the recycling of saponified lanthanum oxide, and most of the remaining lanthanum oxide is sold as a product.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0013] 1. The present invention uses lanthanum oxide solid powder as a saponifying agent and a saponifying extractant. The saponified lanthanum soap organic directly enters the extraction line for extraction and separation. Since lanthanum oxide has strong alkalinity and high purity, when lanthanum oxide solid powder is used to saponify the organic, the saponification reaction is fast and less saponification wastewater is discharged: when lanthanum oxide solid powder is used to saponify the organic, only a small amount of saponification wastewater is generated, and the saponification wastewater does not contain inorganic salt substances, and there is no need to perform wastewater treatment, thereby reducing the cost of wastewater treatment.

[0014] 2. The saponified organic powder of the present invention is pure: the impurity content of the lanthanum oxide solid powder is much lower than that of the existing conventional saponifier. Therefore, the organic-loaded impurity ions after saponification are less, the saponified organic powder is relatively pure, and the impurity ions brought into the extraction line are relatively less, which helps to improve the purity of the extraction line product. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a process flow chart of the present invention;

[0016] Figure 2 This is a simplified process flow chart of organic extraction and separation of lanthanum soap in the present invention;

[0017] Figure 3 This is a process flow chart of organic saponification in the existing rare earth extraction process; DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the drawings and specific data in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0019] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example

[0021] like Figure 1-2 This embodiment provides a method for separating a mixed rare earth chloride solution by organic extraction using lanthanum oxide saponification, comprising the following steps:

[0022] Step 1: Use solid lanthanum oxide powder to saponify blank organic matter. The addition ratio of solid lanthanum oxide powder and blank organic matter is 1m 3 Add 30kg lanthanum oxide to the blank organic; the saponification reaction time is more than 30min, the saponification reaction temperature is 40-60℃, and the organic saponification value is controlled to be 0.5mol / L;

[0023] Step 2: Load La after saponification in step 1 3+ The lanthanum soap organic solution enters the extraction line after standing and clarifying, and is directly used for the extraction and separation of mixed rare earth chloride liquid, such as Figure 2 ;

[0024] Step 3: The lanthanum chloride liquid produced by extraction and separation enters the back-end precipitation process, and undergoes precipitation reaction with ammonium bicarbonate or a mixed precipitant of ammonium bicarbonate and ammonia water to produce lanthanum carbonate, and then the produced lanthanum carbonate is calcined in a natural gas kiln to produce lanthanum oxide;

[0025] Step 4: A small portion of the produced lanthanum oxide is used to saponify blank organic matter to achieve the recycling of saponified lanthanum oxide, and most of the remaining lanthanum oxide is sold as a product.

[0026] In the present invention, for separating mixed rare earth chloride solution, other rare earth oxides cannot replace lanthanum oxide for organic saponification. There are two main reasons. First, the extraction of rare earth ions by P507 belongs to positive sequence extraction, i.e., from La 3+ To Lu 3+ As the atomic number increases, rare earth ions are more easily extracted by P507, so La 3+ It is the least extractable, only saponified organic load La 3+After that, the organic phase will undergo orderly ion exchange with the aqueous phase in countercurrent extraction. 3+ is exchanged into the water phase and comes out of the extract at the front end of the extraction box. 3+ After the ion exchange occurs, the organic matter loaded with other rare earth ions continues to flow backwards and continues to exchange with other rare earth ions, and finally realizes the extraction and separation of all rare earth ions. If other rare earth oxides are used, the extraction and separation of mixed rare earth chlorides cannot be completed, and pure lanthanum chloride will not be produced. Second, because the metallic properties of rare earths decrease from lanthanum to lutetium, lanthanum oxide is the most alkaline among rare earth oxides. Therefore, when lanthanum oxide is used as a saponifier to saponify blank organic matter, the saponification reaction rate is relatively fast, the saponification value can reach the expected value, and the saponification reaction conditions are not harsh, which is easy to apply industrially. In summary, lanthanum oxide is the best choice when using rare earth oxides as saponifiers to saponify blank organic matter.

Claims

1. A method for separating a mixed rare earth chloride solution by organic extraction using lanthanum oxide saponification, characterized in that: The following steps are included: Step 1: Use solid lanthanum oxide powder to saponify blank organic matter. The addition ratio of solid lanthanum oxide powder and blank organic matter is 1m 3 Add 30 kg of lanthanum oxide to the blank organic; Step 2: Load La after saponification in step 1 3+ The lanthanum soap organic solution enters the extraction line after being clarified by standing, and is directly used for extraction and separation of mixed rare earth chloride liquid; Step 3: The lanthanum chloride liquid produced by extraction and separation enters the back-end precipitation process, and undergoes precipitation reaction with ammonium bicarbonate or a mixed precipitant of ammonium bicarbonate and ammonia water to produce lanthanum carbonate, and then the produced lanthanum carbonate is calcined in a natural gas kiln to produce lanthanum oxide; Step 4: A small portion of the produced lanthanum oxide is used to saponify blank organic matter to achieve the recycling of saponified lanthanum oxide, and most of the remaining lanthanum oxide is sold as a product.

2. The method for separating mixed rare earth chloride solution by organic extraction using lanthanum oxide saponification according to claim 1, characterized in that: In step 1, the saponification reaction time is more than 30 minutes, the saponification reaction temperature is 40-60° C., and the organic saponification value is controlled to be 0.5 mol / L.

Images