TWI503418B - A method of removing impurities of gallium by ultrasound extraction and heat treatment - Google Patents

Description

Method for removing impurities in gallium by ultrasonic extraction and heat treatment

The present invention relates to a method for improving the purity of metal gallium, and more particularly to a method for increasing the purity of metal gallium from 99 wt.% to 99.99 wt.% by ultrasonic extraction and heat treatment procedures.

Sparse metals generally refer to seven elements of gallium (Ga), indium (In), thallium (Tl), germanium (Ge), selenium (Se), tellurium (Te), and thorium (Re), of which gallium is in the earth's crust. The content is only 5×10 ^-4 ~ 1.5×10 ^-3 wt.%. However, no minerals with gallium as the main component have been found in the world, and he usually enters other minerals in the form of isomorphous crystals. Gallium is mainly distributed in bauxite, copper sulfide or sphalerite at a very low content. According to statistics, the content of gallium in bauxite is about 0.002~0.02wt.%, and gallium in copper sulfide or sphalerite. The content is about 0.01~0.02wt.%, and the gallium content in the vermiculite is relatively rich, about 0.1~0.8wt.%. In addition, gallium is also present in the coal and sea. The gallium element was discovered in 1875. Used in the production of primary products such as low-melting alloys and high-temperature thermometers. By the end of the 1950s, the annual consumption of the world was less than 100kg. Since the 1960s, gallium has been used in the electronics industry. In addition, the application of metal gallium in mobile communications, personal computers, and the automotive industry is increasing at an average annual rate of 13.6%.

The hardness of gallium is similar to that of lead. It can be cut with a knife and has a low melting point (melting point 29.78 ° C). It can be dissolved by placing it in the palm of a hand. In general, liquid gallium exhibits a silvery white color. However, gallium with a low melting point has a boiling point of 2403 ° C. The difference in melting point and boiling point is unique among all metals, and gallium has good superconductivity at low temperatures. Alloys of gallium with vanadium, niobium, and zirconium are also superconducting; however, gallium is the opposite of most metals, and the density of liquid gallium (6.0 g/cm3) is larger than that of solid gallium (5.9 g/cm3), so when it is liquid gallium When solidified, the volume will increase by 3.2%. Therefore, metal gallium should be stored in a flexible plastic bottle. In addition, gallium has the ability to absorb neutrons. In the atomic reactor, gallium can be used to control the number of neutrons and the reaction rate. With the rapid development of IT technology, semiconductor materials have completed the first generation of semiconductor germanium and second-generation semiconductor gallium arsenide and third-generation semiconductor gallium nitride, gallium and its representative 3 to 5 compound excellent properties in this field It will begin to play a role, and its application range will continue to expand. High temperature thermometers, fire protection devices, information storage devices, optical materials, semiconductor materials and solar cell materials are all common applications of gallium.

In addition, the physical properties and applications of gallium include: the vapor pressure is very low, only 10 ^-3 Pa at 1000 ° C, so it can be used as a sealing liquid in a vacuum device; gallium can improve the hardness of some alloys, and can improve the magnesium alloy Abrasion resistance; gallium compounds can be used as catalysts for analytical chemistry, organic synthesis, and drug synthesis; radioactive gallium can be used to diagnose cancer; gallium is also commonly used to make indental alloys. Adding less than 17.5% gallium to copper can increase its strength, hardness and electrical resistance, but adding too much will make the copper alloy brittle; adding gallium to cadmium will lower the vapor pressure and help to extend the service life of the arc lamp. The general alloy coated with gallium is corrosion resistant. Because some gallium-based low-melting alloys are liquid and non-toxic at room temperature, they can replace vacuum diffusion and some instruments usually use mercury or mercury seals. These low-melting alloys can also be used as metal coatings, such as on mirrors. The gallium-based reflectance is still higher than 88% at temperatures above 300 °C and can operate normally. In addition, gallium is also used in the fields of medicine and biology in the form of gallium nitrate or gallium chloride for the diagnosis and treatment of malignant tumors, advanced hypercalcemia and certain bone diseases. Gallium chloride is also an additive to the metallurgical industry. With the development of the electronics industry and the defense industry, the use of gallium and its compounds has gradually expanded.

As can be seen from the above, gallium metal can be used in many industries and fields. Therefore, how to extract high-purity gallium metal from such a variety of raw materials has become a very important issue. The existing technology can improve the purity of home metals. Up to 99wt.%, but there is still room for improvement in purity. In addition, how to purify more efficiently is also an urgent problem to be solved. In view of this, the creators of this case have accumulated experience based on years of research and matched themselves. With the creativity and constant experimentation, a method for removing impurities in gallium by ultrasonic extraction and heat treatment which can effectively improve the purification efficiency is developed.

The main object of the present invention is to provide a method for removing impurities in gallium by ultrasonic extraction and heat treatment, which can effectively improve the extraction purity which can be achieved by the original extraction technology, and improve the extraction purity from 99 wt.% to 99.99 wt. %, the method for removing impurities in gallium by ultrasonic extraction and heat treatment, the steps comprising: step S1: raising the temperature above the melting point of the elemental gallium to make the elemental gallium liquid; step S2: making the liquid gallium and acid full After mixing, put it into ultrasonic oscillation In the device, the hole effect generated by the ultrasonic wave is used to accelerate the dissolution of the impurity into the acid solution; step S3: repeating the operation step S2 to extract the impurity in the gallium; and step S4: the gallium purified by the ultrasonic extraction method It is placed in a high-temperature furnace, and is heated by an inert gas to remove impurities having a lower boiling point than metal gallium; and step S5: after the heat treatment is completed, metal gallium having a purity higher than 99.99% can be obtained.

In order to more clearly describe a method for improving the purity of metal gallium by ultrasonic extraction and heat treatment proposed by the present invention, a preferred embodiment of the present invention will be described in detail below with reference to the drawings.

Please also refer to the first figure, which is a schematic diagram of a first method step of the method for improving the purity of metal gallium by using ultrasonic extraction and heat treatment, and the steps thereof include: step S1: increasing the temperature of a raw material gallium to elemental gallium The melting point (29.78 ° C) or higher makes the elemental gallium in the raw material gallium liquid. In the first method, the temperature can be set at 50.0 ° C. At this time, the metal gallium is still in a liquid state, and the tin contained in the raw material gallium, The nickel or iron metal is still solid, so that the metal impurities can be removed first; step S2: the liquid gallium is thoroughly mixed with the acid solution. In the first method, the acid solution is diluted with 4N nitric acid, after mixing , placing the solution In a supersonic oscillator, the hole effect generated by the ultrasonic wave is used to accelerate the impurity in the raw material gallium into the acid solution, thereby further improving the extraction purity of the gallium; step S3: repeating the operation step S2, the gallium is further processed The impurities in the medium are continuously taken out and dissolved in the acid solution; Step S4: the gallium purified by the ultrasonic extraction method is placed in a high-temperature furnace, in the first method, 1000 ° C, and an inert gas (such as helium gas) is introduced. Then, heat treatment is performed to remove impurities having a boiling point or a sublimation point lower than that of the metal gallium; and step S5: after the heat treatment is completed, metal gallium having a purity higher than 99.99% can be obtained.

Please refer to the second figure, which is a schematic diagram of a second method step of the method for improving the purity of metal gallium by using ultrasonic extraction and heat treatment, and the steps thereof include: step S1: increasing the temperature of a raw material gallium to elemental gallium The melting point (29.78 ° C) or higher makes the elemental gallium in the raw material gallium liquid. In the second method, the temperature can be set at 50.0 ° C. At this time, the metal gallium is still in a liquid state, and the tin contained in the raw material gallium, The nickel or iron metal is still solid, so that the metal impurities can be removed first; step S2: the liquid gallium is thoroughly mixed with an acid solution, and in the second method, the acid solution is diluted with a concentration of 4N nitric acid, after mixing , placing the solution in an ultrasonic oscillator and using the holes generated by the ultrasonic waves The effect is that the impurities in the raw material gallium are acceleratedly dissolved into the acid liquid, thereby further improving the extraction purity of gallium; step S3: the step S2 can be repeatedly performed, and the impurities in the gallium are continuously taken out and dissolved in the acid liquid; step S4': The gallium purified by ultrasonic extraction is placed in a high-temperature furnace, in the second method, 1000 ° C, and subjected to a decompression process to a pressure of atmospheric pressure, followed by heat treatment to remove the boiling point or sublimation point lower than that of metal gallium. Impurity; and step S5: After the heat treatment is completed, metal gallium having a purity higher than 99.99% can be obtained.

The above-described method steps of the present invention have been fairly completely disclosed. Next, in order to confirm that the method steps of the present invention in the above embodiments are indeed effective, experimental test data under different processing conditions will be provided below to prove the present invention. For improving the purity of the extracted gallium metal, please refer to the third figure, which is a schematic diagram of the first and second experimental conditions of the present invention, wherein the extraction conditions of the first experimental condition are that the raw material gallium is mixed at a ratio of 1:20. Extracted in a concentration of 4N nitric acid and extracted in an ultrasonic oscillator at 50 ° C for 30 minutes, and then the mixed liquid graphite crucible is placed in a high temperature furnace for heat treatment procedures, and in the program in a high temperature furnace The helium gas (氦 flow rate 100 mL/min) was introduced and treated at 1000 ° C for one hour. As shown in the table, it can be clearly seen that the total concentration of impurities is reduced to 93.3 ppm below. In other words, the purity of gallium has been reached. More than 99.99%; next continue to compare the data generated under the second experimental conditions, the second experimental conditions and A different experimental condition is that the solution is placed in an ultrasonic oscillator for extraction for 90 minutes during extraction. It can be seen from the table that the concentration of the impurity is reduced to 75.7 ppm, which is more than the first embodiment, so it can be known that the extraction is performed. The longer the time, the higher the purity of the added metal.

Finally, please refer to the fourth figure, which is a schematic diagram of the third and fourth experimental condition data of the present invention, wherein the third experimental condition is different from the second experimental condition in that the step of introducing helium in the heat treatment procedure is replaced by decompression. The procedure, that is, in a reduced pressure environment (2 torr) at 1000 ° C for one hour, from the table, the concentration of impurities is reduced to 63.5 ppm, the purification effect is better than the second experimental conditions, so that the extraction can be proved A good purification effect can be achieved by heating in a reduced pressure environment; finally, the fourth experimental condition and the third experimental condition are compared, and the difference is that the fourth experimental condition is to replace 4N nitric acid at the time of extraction. 4N hydrochloric acid, as shown in the table, the concentration of the impurity is 99.5ppm, which means that the purity of the gallium metal is still above 99.99%, but the purity is lower than the first, second and third experimental conditions. Therefore, it can be proved that the use of nitric acid as a mixed raw material gallium acid solution is better than the use of hydrochloric acid.

Finally, it should be specially stated that in the heat treatment process, zinc, phosphorus with a boiling point lower than 1000 ° C, and arsenic which will sublimate at 613 ° C, after ultrasonic vibration of the acid solution, are subjected to heat treatment at 1000 ° C, and the final concentration is 0; comparing the second experimental condition and the third experimental condition, it can be found that the heat treatment by heat treatment instead of the helium atmosphere heat treatment, the total concentration of impurities will decrease by 16.1% (75.7 ppm → 63.5 ppm), and the boiling point of lead and lead is lower. The concentration decreases by a large margin.

It can be confirmed from the above description that the extract liquid which changes the heat treatment condition and the ultrasonic oscillation can have the effect of reducing the impurities in the gallium to different degrees, because the hole effect generated by the ultrasonic oscillation is favorable for the impurity to be removed from the gallium, and at a high temperature. In the environment, metals with lower boiling or sublimation points can also be efficiently removed from gallium.

In summary, it can be seen that the present invention has the advantage that only 99 wt.% of gallium metal can be extracted to 99.99 wt.% in the prior art by using the above-mentioned step method and control of experimental conditions.

However, the detailed description of the present invention is intended to be illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention. The patent scope of this case.

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The first figure is a schematic diagram of a first method step of a method for improving the purity of metal gallium by using ultrasonic extraction and heat treatment; the second figure is a method for improving the purity of metal gallium by using ultrasonic extraction and heat treatment of the present invention. 2 is a schematic diagram of the steps of the method; the third diagram is a schematic diagram of the first and second experimental conditions of the method for improving the purity of metal gallium by using ultrasonic extraction and heat treatment; and the fourth diagram is improved by ultrasonic extraction and heat treatment of the present invention. Schematic diagram of the third and fourth experimental condition data for the method of metal gallium purity.

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Claims (6)

A method for improving the purity of metal gallium by ultrasonic extraction and heat treatment, the steps comprising: step S1: increasing a raw material gallium temperature above a melting point of the elemental gallium to make the elemental gallium in the raw material gallium liquid; step S2: The liquid gallium is thoroughly mixed with an acid solution and placed in an ultrasonic oscillator, and the hole effect generated by the ultrasonic wave is used to accelerate the dissolution of the impurity into the acid solution; Step S3: repeating the operation step S2, the gallium is The impurity is taken out; step S4: placing the gallium purified by the ultrasonic extraction method into a high-temperature furnace, and passing the inert gas, followed by the decompression process to under atmospheric pressure, followed by heating for at least one hour. Processing to remove impurities having a lower boiling point than metal gallium; and step S5: after the heat treatment is completed, metal gallium having a purity higher than 99.99% can be obtained. The method for improving the purity of metal gallium by ultrasonic extraction and heat treatment according to the first aspect of the patent application, wherein in the step S1, the temperature setting may be higher than the melting point of the elemental gallium (29.78 ° C) and impurities are contained therein. Between the melting points of the lowest melting point material, the metal gallium is made into a liquid state in this environment, and other impurities are solid. The method for improving the purity of metal gallium by ultrasonic extraction and heat treatment according to claim 1, wherein the acid solution in the step S2 may be any one of the following combinations: nitric acid, hydrochloric acid, sulfuric acid, and the like. An acid solution having a solution pH of less than 7. The method for improving the purity of metal gallium by ultrasonic extraction and heat treatment according to claim 1, wherein when the step S2 is repeated, the acid solution can be carried out from any of the following combinations. Replacement: nitric acid, hydrochloric acid, sulfuric acid and acid solution that can make the solution pH less than 7. The method for improving the purity of metal gallium by ultrasonic extraction and heat treatment as described in claim 1, wherein the inert gas introduced before the heat treatment described in the step S4 may be any of the following combinations. One type: helium, neon and argon. The method for improving the purity of metal gallium by ultrasonic extraction and heat treatment according to claim 1, wherein the inert gas may be any one of the following combinations: helium, neon, and Argon.