JPH04180801A - Continuous operation of solvent extraction - Google Patents

Abstract

PURPOSE:To ensure that continuous solvent extraction can be performed by taking out a mixture of oil and water containing a sediment generated in an oil and water interface in a settlement tank of a mixer settler, from the settlement tank, then filtering said mixture continuously using a filtration assistant, and circulating filtrate through a device. CONSTITUTION:A mixture of oil and water containing a sediment generated in the oil and water interface of a settlement tank for a mixer settler which is an extraction device, is taken out of the settlement tank at a ratio of about (5-1)/10 times a liquid amount sent to a next-stage mixer settler. Next, the mixture of oil and water containing said sediment is continuously filtered with the help of a filter using a filtration assistant containing ashless pulp and activated carbon with a particulate size of 1 to 100mum at a weight ratio of 1:10 to 10:1. Then the filtrate is circulated in the mixer settler. As a result, it is possible to enhance extraction efficiency, separation efficiency and contact efficiency and thereby make possible the continuous performance of solvent extraction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for continuous operation of solvent extraction.

(Prior art and its problems) Solvent extraction is the separation, concentration, and purification of organic and inorganic substances by contacting liquids consisting of two different phases, water and oil. It is starting to be used.

During actual operation of solvent extraction, precipitates and floating substances called third phase or crud are generated at the oil/water interface due to the decomposition of organic matter due to liquid-liquid contact and the contamination of solids such as silica from the feed liquid.

Since these precipitates collect at the oil/water interface, they are not removed from the system and accumulate within the apparatus.

If the amount generated is small, operational problems are unlikely to occur, but
As the amount of precipitate increases, problems arise such as a decrease in extraction rate, a decrease in separation efficiency, and contamination with impurities.

Moreover, if the amount of precipitates becomes even larger, operation becomes impossible and work to remove the precipitates becomes necessary.

The precipitates that occur at this oil/water interface are oxidized organic substances or insoluble precipitates that combine organic substances and metals.
Many non-crystalline, glue-like amorphous precipitates occur.

When removing amorphous precipitates by filtration, they quickly become clogged, so the filter material must be replaced many times.
Processing required a lot of effort and time.

(Objective of the Invention) The present invention was made in view of the above-mentioned circumstances. During continuous solvent extraction, the precipitate that accumulates at the oil/water interface is removed together with the oil/water mixture, and a filter aid is removed. The purpose of the present invention is to provide a method for continuous operation of solvent extraction by using a mixture of oil and water, performing continuous filtration, and circulating the mixed filtrate of oil/water into a mixer settling tank again.

(Means for Solving the Problems) The present invention provides a method for continuously operating solvent extraction, in which an oil/water mixture containing a precipitate generated at the oil/water interface in a settling tank of a mixer settler, which is an extraction device, is settled. The oil/water mixture containing the precipitate is removed from the tank, continuously filtered using a filter aid mixed with ashless pulp and activated carbon, and the filtrate is circulated again into the tank of the mixer settler. This is a continuous operation method for solvent extraction.

The continuous operation method of the present invention is not limited to solvent extraction systems (it is effective in removing precipitates that accumulate at oil and water interfaces, and can be applied to all kinds of extractions, such as inorganic extraction and organic extraction. It is something.

The amount of oil/water mixture containing sediment taken out from the settling tank should be about 5 to 1/1O times the amount of liquid sent from the settling tank to the next stage mixer-settling device, and the preferred amount is the amount of sediment that accumulates. It is best to take it out to the extent that it does not increase.

The oil/water mixture ratio of the mixed liquid taken out is 1:10 to 10.
One against one is better.

This is because when the water and oil extraction ratio is extremely large, the oil/oil
This is because the phase ratio of water changes greatly, which may affect the extraction rate.

Oil/water mixtures containing precipitates are filtered, but since the precipitates are glue-like, if the filter material used has large mesh, it will pass through the filter, whereas if the mesh is small, it will quickly become clogged. Since continuous filtration is not possible, using a filter aid made of a mixture of ashless pulp and activated carbon prevents clogging during filtration and further improves extraction efficiency and separation efficiency. However, there is less contamination of impurities.

The reason is that the absence of precipitates at the oil/water interface improves the contact efficiency and, accordingly, the extraction efficiency.

Furthermore, since there is no precipitate, there is no entanglement or adsorption of impurities to the precipitate, which improves the separation efficiency.

In the present invention, the reason for using a filter aid that is a mixture of activated carbon and ashless pulp is that activated carbon alone causes clogging;
This is because ashless pulp alone will pass through the filtration, but when an appropriate amount of activated carbon and ashless pulp are mixed, the activated carbon will fill the fibrous gaps of the ashless pulp, creating a layer of filter aid that is effective for filtering organic content. This makes filtration easier.

The mixing ratio of activated carbon and ashless pulp is 1:1° to 10 by weight.
:1, and if the activated carbon ratio is small, clogging and filtration are likely to occur. Because it will disappear.

In addition, the required layer or amount of filter aid is related to the precipitate to be filtered, but approximately 0.01 of the precipitate is
~ several wt% is sufficient.

Hereinafter, examples related to the present invention will be described, but the examples are not intended to limit the present invention.

(Example 1) A hydrochloric acid solution containing palladium chloride and an organic solvent containing diethylhexyl sulfide were brought into contact with each other in a mixer settler having a volume of IOA while being supplied at a rate of 500 yd/min, and palladium was extracted with the solvent, The mixed liquid at the oil/water interface containing the precipitate generated in the settling tank of the mixer settling apparatus is mixed with 100% of the oil/water ratio of 1:1.
d/min amount continuously, filtration area 1000cn
f, activated carbon (Shirasagi:
0.05% of the oil/water mixture containing the above-mentioned precipitate was continuously applied to the oil/water mixture containing the precipitate using a filter aid consisting of a mixture of ashless pulp (manufactured by Takeda Pharmaceutical Industries, Ltd.) and ashless pulp (manufactured by Atoppanczyk) at a weight ratio of 1:1. The filtered mixture was again circulated into the mixer settler.

The extraction efficiency for 24, 48, and 72 hours of extraction operation is 9, respectively.
It was stable at 6.95.953o, the oil phase and the aqueous phase were separated well, no accumulation of precipitates was observed, and no clogging occurred on the filter surface.

(Example 2) A hydrochloric acid solution containing palladium chloride and an organic solvent containing diethylhexyl sulfide were each added at 500 rnl/
The oil/water interface mixture containing the precipitate generated in the mixer settler tank of the mixer settler device is then brought into contact in a mixer settler having a volume of IM, and the palladium is extracted with a solvent. 150 from the ratio of water to 5
Continuously take out the amount of m1/min, filtration area] 000c
NF, activated carbon (Shirasagi) using a filter with a retention particle size of 15 mm.

0.02% of the oil/water mixture containing the precipitate was applied to the oil/water mixture containing the precipitate through continuous filtration using a filter aid made by mixing 6:40 weight ratio of ashless pulp (manufactured by Takeda Pharmaceutical Industries, Ltd.) and ashless pulp (manufactured by Atoppanczyk) at a weight ratio of 0.02%. The filtered mixture was again circulated into the mixer settler.

The extraction efficiency for 24, 48, and 72 hours of extraction operation is 9, respectively.
It is stable at 6.96.95% and has good separation between the oil phase and water phase.
No accumulation of precipitate was observed, and no clogging occurred on the filtration surface (conventional example). When the operation was performed in the same manner as in Example I except that no filtration operation was performed, extraction after 8.16.24 hours. Efficiency is 95.91
．． It gradually decreased to 85%, and after 48 hours, a large amount of precipitate accumulated in the mixer settler, making it virtually impossible to operate.

(Reference Example) When the same operation as in Example 1 was performed without using a filter aid, the filtration surface became clogged during continuous operation for 8 hours, making filtration difficult.

(Effects of the Invention) As is clear from the above explanation, the continuous operation method for solvent extraction of the present invention extracts the precipitate generated at the oil/water interface in the settler tank of the mixer settler as an oil/water mixture and filters Extraction efficiency, separation efficiency and contact efficiency can be improved by continuously filtering the oil/water mixture using a mixture of ashless pulp and activated carbon as the agent and circulating the filtered oil/water mixture back to the mixer settler device. It is said to be extremely industrially effective as it enables continuous solvent extraction.

Applicant: Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (1)

[Claims] (1) In a method of continuous solvent extraction, an oil/water mixture containing a precipitate generated at the oil/water interface in the settling tank of a mixer settler, which is an extraction device, is taken out from the settling tank and mixed with ashless pulp and activated carbon. 1. A method for continuous operation of solvent extraction, characterized in that the oil/water mixture containing the precipitate is continuously filtered using a filter aid obtained by using the same method as above, and the filtrate is circulated again into a tank of a mixer settler.