Copper solvent extraction reagent, Nickel Cobalt extractant, D2EHPA & Rare earth leaching solvent

Introduction to Solvent Extraction No. 260

by:Deyuan      2021-03-05

The basic principle of 260 solvent oil extraction
 Solvent extraction method is also called-liquid extraction method, referred to as extraction method. In the extraction method, the organic phase and the water phase are mixed with each other. After the substances to be separated in the water phase enter the organic phase, the two phases are separated by the difference in mass density of the two phases. The organic phase is generally composed of three substances, namely extractant, diluent, and solvent. Sometimes some regulators are added to the extractant to make the performance of the extractant better. The extraction of non-ferrous metal cyanide complexes from the solution generally uses polymer organic amines, such as chlorinated trialkylmethylamine (N263), the diluent is higher alcohol, and the solvent is sulfonated kerosene. The water phase is the wastewater to be treated. 260 mineral spirits is widely used as a common metal extractant.

The role of 260 solvent oil in industrial metallurgy

There are two main industrial metallurgical methods, namely fire method and wet method, of which hydrometallurgical technology is the most widely used. The hydrometallurgical technology refers to the transfer of various valuable elements from the solid phase to the liquid phase through the leaching process, and then the separation and recovery of valuable components from the leaching liquid through various effective methods. The separation and recovery of non-ferrous metals and rare earth elements from the leaching liquid by extraction is the most commonly used process in the hydrometallurgical industry. However, when the metal elements are recovered from the leachate by the extraction process, a large amount of raffinate wastewater will also be generated. The organic matter in the raffinate wastewater is complex, with high COD content and high toxicity. It must be pre-treated to remove COD before discharge.

  In the hydrometallurgical industry, the commonly used metal extractants mainly include acid extractants, neutral extractants, alkaline extractants and oxime type extractants. Among them, acidic extractants such as P204 and P507 are often used to extract and separate non-ferrous metal elements such as nickel and cobalt; neutral extractants such as TBP are often used to extract and separate rare earth elements; alkaline extractants such as primary amines N235, N1923, etc. are often used for extraction and recovery Vanadium, chromium, tungsten, molybdenum, etc.; oxime extractants such as LIX984 are commonly used in the extraction and recovery of copper.

   In actual production, the above-mentioned various extractants need to be used in a certain concentration of extraction organic phase with diluents such as No. 260 solvent oil sulfonated kerosene. In this way, the components embodied as COD in the raffinate wastewater mainly include extractants, diluents, and metal extract compounds that are dissolved in the water phase. Taking the molybdenum extraction process of an enterprise as an example, the organic matter in the raffinate wastewater includes a small amount of dispersed oil, extractant N235, soluble sulfonated kerosene and molybdenum extract compound. Except for COD, the salt content in the general raffinate wastewater is usually high. Anions mainly include sulfate, phosphate, nitrate, carbonate, chloride, fluoride and other heavy metal ions, which are not suitable for biodegradation. deal with. The inventor’s previous research found that the oil separation, air flotation, resin and activated carbon adsorption technologies have no obvious effect on the removal of COD from various raffinate wastewaters in the hydrometallurgical industry; Fenton, electric Fenton, electrolytic oxidation, and ozone oxidation are used Various advanced oxidation technologies can remove the COD in the raffinate wastewater to about 200mg/L at most, but the use of activated carbon or activated coke adsorption still cannot further remove COD to below 100mg/L. This shows that the organic matter in the wastewater treated by Fenton and other advanced oxidation technologies are mainly small molecules with strong polarity, which are extremely difficult to further degrade.

   In order to ensure that the COD of the raffinate wastewater in the hydrometallurgical industry meets the standard and reduce the treatment cost, there is an urgent need for a method that can remove the COD of this wastewater to below 100mg/L.

Most extractants in the industry are dissolved in organic solvents. Common organic solvents are sulfonated kerosene, 260 solvent oil, and 406# environmentally friendly solvent oil. And it has a synergistic effect on the extractant because it contains a small amount of aromatic hydrocarbons. Soluble in organic solvents can also improve the extraction capacity of the extractant, enhance the solubility of its metal extracts, reduce viscosity, reduce its volatility, and reduce its solubility in water. Extractants are mainly used in non-ferrous metal hydrometallurgical industries, such as copper, zinc, cobalt nickel, cadmium, gold and silver, platinum metals, rare earths and other industries. The main functions of the extractant include: separating the main metal and impurity metal ions, enriching the concentration of the main metal ion, purifying the metal ion, and changing the type of anion. Metal extractants are mainly seven kinds of common hydrogen ions such as phosphoric acid, ammonium salt, benzene, etc., or hydroxyl groups are replaced by long-chain alkyl groups. When the metal is combined with these extractants, it becomes a metal organic compound and dissolves in an organic solvent. Due to the different binding abilities of various metals with these extractants, the sequence of extracting metals by these extractants is different, thereby separating these metal ions. The main factors affecting the extraction sequence of metal ions are: the valence state of the metal ion, the size of the metal ion radius, the hydration energy of the metal ion, the stabilization energy of the d electron, and the coordination number. For the extractant: acidity, steric hindrance, and lipophilicity of the extractant all affect the extraction sequence of metal ions. The extraction operations mainly include: 1. Adjust the pH of the feed liquid. For example, in cobalt-nickel metallurgy, the general material liquid is adjusted to pH 3.4-4.0. Second, the configuration of the extractant, the extractant is configured according to a certain ratio of the extractant and the organic solvent V/V. For example, P204 extractant, generally P204 extractant and sulfonated kerosene organic solvent V/V=4:1 are used to configure the extractant. 3. Saponification, mainly for acidic extractants. That is, a certain extractant reacts with alkali. The main purpose is to stabilize the pH of the feed liquid and enhance the extraction capacity of the extractant. 4. Extract metal ions. Industry generally uses countercurrent extraction process. That is, the organic and water phases flow in opposite directions. Generally there will be extraction stages. This can ensure the efficiency of extraction. 5. Washing. This is mainly from the consideration of impurity removal, washing the impurity metal ions with the subsequent extraction sequence into the water phase to ensure the purity of the organometallic ions. 6. Washing with water mainly considers the problem of phase separation and entrainment in extraction. Seven, back extraction. With a certain acid, the metal is back-extracted from the organic to the water phase again.

Application of 260 solvent oil wet extraction in copper smelting

  No.260 solvent oil wet extraction oil is the solvent oil obtained by wet extraction, such as the mine solvent oil operated by our company, that is, the wet extraction oil. It is reported that wet extraction also has mature applications in other industries, such as copper extraction.

   Look at how the copper extraction company staff describe the application of wet extraction:

   Compared with traditional fire smelting, hydro smelting has the advantages of low energy consumption, less pollution, less negative impact on the environment, and good sustainable development. But this requires a prerequisite, that is, the extraction system must operate well and be able to always be in a healthy virtuous circle. At this point, foreign companies generally do better than domestic companies.

Most of the organic phases of domestic hydrometallurgical copper smelting enterprises have not been running for a few years, and such problems will occur, which will cause the interruption of system operation, and then have to stop production to solve the problem; while the organic phases of foreign companies that have operated well have been running for 20 years. Even 30 years have still maintained good quality and performance.

   The reason for this may be mainly due to two aspects. First, foreign wet smelting started early, the technology is relatively mature, and the accumulated experience is more abundant; while the domestic started late, the technology is relatively backward, and the experience is relatively lacking.

Second, foreign companies pay more attention to all aspects of the L-SX-EW plant, and are willing to invest in the removal of PLS, the purification of the organic phase, and the optimization of the extraction process. They pay attention to the sustainability of the system operation, and more Pay attention to the long-term development of enterprises; while most domestic enterprises are not willing to invest in PLS, organic phase purification and impurity removal, and optimization of extraction process, but they attach great importance to short-term economic benefits, as long as the system can barely run to produce economic benefits , They will not care about the unfavorable changes that are taking place in the extraction system and the serious consequences that they may face.

In order to make hydrometallurgy a veritable environmentally friendly smelting process, it is necessary to pay attention to the quality maintenance and performance maintenance of the organic phase of the extractant in the daily operation process, and timely remove degradation products and impurities from the extraction system. And continuously optimize the extraction process, reduce the entrainment of organic phases, reduce the pollution of organic relative to the environment, and make the system truly environmentally friendly, healthy and sustainable operation.
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