A beryllium ore smelting process based on a medium and high frequency induction furnace

Abstract

The present invention belongs to the technical field of metallurgical separation and purification, and relates to a beryllium ore smelting process based on a medium and high frequency induction furnace, which comprises the following steps: A. Crushing: Mixing beryllium ore and a flux and then performing crushing, and controlling the particle size of the crushed mixed material to be between 1 mm and 250 mm; B. Batching: Adding a conductive agent to the mixed material, mixing evenly, adding it to the medium and high frequency induction furnace, and introducing nitrogen for smelting, and controlling the frequency of the medium and high frequency induction furnace to be between 4500 Hz and 20000 Hz. The method for smelting beryllium ore by using a medium and high frequency induction furnace proposed by the present invention reduces power consumption and water consumption, and the number of furnace treatments of the crucible is increased by more than 30%; the conversion rate of beryllium in the furnace charge is increased, the conversion rate of beryllium exceeds 99%, and the comprehensive recovery rate of beryllium is increased by more than 12% compared with the conventional sulfuric acid method for beryllium smelting, and the quality requirement of preparing a high-purity beryllium oxide product without adding a purification step for beryllium oxide is successfully achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical separation and purification, and particularly relates to a beryllium ore smelting process based on a medium and high frequency induction furnace. Background Art

[0002] The existing methods for treating beryllium ore are mainly the sulfuric acid method, also known as the Degussa method. Beryl is one of the beryllium ores for smelting and recovering beryllium in China. It is a very stable compound. Except for hydrofluoric acid, other mineral acids or alkalis cannot directly decompose it. In order to decompose beryl, the beryllium ore is first mixed with calcite and then smelted in an electric arc furnace at a temperature of 1500 - 1700 °C to destroy the crystal form of beryl. The obtained fine beryllium glass is acidified and leached with sulfuric acid, and then through a series of complex steps such as evaporation crystallization for purification of aluminum removal, neutralization for impurity removal, roasting, etc., industrial grade beryllium oxide is obtained. The beryllium extraction production process of China Minmetals Beryllium Co., Ltd. adopts the electric arc furnace plus flux smelting method, and its technological process is: ore + calcite → smelting → acidification leaching → evaporation crystallization → neutralization for iron removal → precipitation → beryllium hydroxide → calcination. However, in production, the electric arc furnace smelting has the following disadvantages: 1. The electric arc furnace generates heat by the arc light between the electrodes, and the highest temperature can reach 2000 °C or above. The material temperature is low in the places without arc light, and the temperature is uneven, resulting in a low ore conversion rate, only about 96%; 2. It can only process lump ore and is not very adaptable to processing fine ore; 3. When the electric arc strikes in the smelting furnace, a large amount of fine ore overflows from around the electrode holes on the furnace cover, causing material loss, polluting the environment, and also causing beryllium poisoning to endanger the health of operators; 4. The molten material at high temperature erodes the furnace lining severely, reducing the quality of the fine beryllium glass and shortening the furnace life. To prevent the outer shell from burning through, the outer shell is cooled with a large amount of cold water during the furnace operation, resulting in extremely high energy consumption.

[0003] An induction furnace is a device that uses the principle of electromagnetic induction to heat ferromagnetic materials for smelting or heat treatment. Ferromagnetic materials generate eddy currents under the action of the alternating magnetic field generated by the induction coil. The eddy currents generate heat under the action of the resistance of the material, thereby heating to increase the temperature of the object. Medium and high frequency induction furnaces have the advantages of high thermal efficiency, fast heating speed, clean production environment, low pollution, easy temperature adjustment, and less alloy element burning loss. At the same time, due to the existence of electromagnetic stirring, the composition and temperature of the molten metal are uniform, and it is widely used in industrial production and scientific research.

[0004] However, since beryllium ore is a material that is neither conductive nor thermally conductive and is a poor conductor, it cannot directly use an induction furnace to heat the beryllium ore itself, but smelts the beryllium ore by heating the crucible.

[0005] CN 216205222 U discloses an induction furnace for ore smelting, including a furnace body. There is a feed inlet at the upper part of the furnace body. A graphite crucible is arranged inside the furnace body. A heating coil is wound around the outer wall of the graphite crucible. An emergency port inclined upward is arranged at the upper part of the graphite crucible. A discharge port leading to the outside of the furnace body is arranged at the middle part of the graphite crucible. This utility model uses the induction furnace to heat the graphite crucible, and gradually melts the ore in the crucible through the conduction of the crucible. The temperature in the furnace is uniform, which improves the conversion rate of the ore. The crucible is not easily eroded by the molten furnace charge, thus being beneficial to improving the conversion rate of fine beryllium glass. However, this method does not solve the consumption of the raw material carbon used to prepare the graphite crucible reacting with oxidants, carbon dioxide or oxygen under high-temperature smelting conditions, nor does it solve the corrosion of the exposed part of the upper crucible directly contacting the air and reacting with oxygen in the air during smelting. The service life of the graphite crucible is not extended for a long time. At the same time, it also does not solve the problems of poor electrical and thermal conductivity of the unmolten beryllium ore, long smelting time of the beryllium ore, and high production cost. Summary of the Invention

[0006] The purpose of the present invention is to provide a beryllium ore smelting process based on a medium-high frequency induction furnace.

[0007] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0008] A beryllium ore smelting process based on a medium-high frequency induction furnace includes the following steps:

[0009] A. Crushing: Mix beryllium ore and flux and then crush them. The particle size of the crushed mixed material is controlled between 1 mm and 250 mm.

[0010] B. Batching: Add a conductive agent to the mixed material. After mixing evenly, add it to the medium-high frequency induction furnace. Continuously introduce an inert gas during the smelting process and carry out smelting. Control the frequency of the medium-high frequency induction furnace to be 4500 Hz - 20000 Hz.

[0011] Since beryllium ore is a material that is neither electrically conductive nor thermally conductive and is a poor conductor, therefore, a conductive agent is added to the ore so that the induction furnace can be directly used for heating the beryllium ore mixture for smelting. Secondly, during the smelting process, a high temperature is generated at the contact position between the ore and the graphite crucible, and the graphite crucible at the contact position is easily oxidized. Therefore, through multiple experiments, the inventor creatively introduces an inert gas into the graphite crucible to protect the surface of the graphite crucible through the inert gas, reducing the possibility of contact between the graphite crucible and oxygen in the air, reducing the reaction between C and O2, and greatly extending the service life of the graphite crucible. The chemical equation for the reaction of the graphite crucible with oxygen in the air is as follows:

[0012] C + O2 → CO;

[0013] C + O2 → CO2;

[0014] C + CO2 → CO.

[0015] In one preferred embodiment, the flux is limestone or calcite.

[0016] The difference between calcite and limestone lies in their different organizational structures. Although both calcite and limestone are calcium carbonate, their organizational structures are different. Calcite has a crystal structure, while limestone is a mixture with a non-crystalline structure. Calcite decomposes into CaO and CO2 at a temperature of 1000 - 1300 °C; the decomposition temperature of limestone is 600 - 900 °C, and that of ordinary limestone is about 900 °C. In traditional beryllium ore smelting, an electric arc furnace is used for smelting, and the smelting time for each furnace exceeds 3 hours. In the present invention, since the smelting time is shortened to 15 minutes, using easily decomposable calcite and limestone can also meet the smelting requirements of beryllium ore.

[0017] In one preferred embodiment, the particle size of the mixed material is controlled within 1 mm - 200 mm.

[0018] If the particle size is too small, the dust increases, polluting the environment and making it easy to be poisoned by beryllium. In addition, if it is too small, calcite and limestone will decompose completely at a lower temperature and in a shorter time, failing to achieve the purpose of complete reaction with beryllium ore, and the conversion rate of beryllium will deteriorate; if it is too large, it cannot be completely mixed with beryllium ore, the reaction will not be complete, and the beryllium conversion rate will decrease.

[0019] In one preferred embodiment, the conductive agent is graphite or activated carbon.

[0020] Since graphite and activated carbon are good conductors of heat and electricity, while beryllium ore and flux are poor conductors of heat and electricity, in a medium-high frequency induction electric furnace, both the graphite crucible and the conductive agent can be used as the heating bodies for the induction current. This can make the temperature in the smelting furnace and within the beryllium ore material more uniform, improving the conversion rate of beryllium in the furnace charge. The conversion rate of beryllium exceeds 99%, improving the comprehensive recovery rate of beryllium. At the same time, the conductive agent is also a reducing agent, which can react with CO2 produced by the decomposition of the flux to generate CO, reducing the corrosion of the graphite crucible by CO2. The reaction equations are as follows, further extending the service life of the graphite crucible and reducing the production cost. In the present invention, the used and discarded graphite crucibles can also be utilized as the conductive agent, achieving resource recycling and reducing the production cost.

[0021] CaCO3 → CaO + CO2↑;

[0022] C + CO2 → 2CO.

[0023] In one preferred embodiment, the mass ratio of beryllium ore, flux, and conductive agent is 1:0.45 - 0.65:0.05 - 0.10.

[0024] If the proportion of beryllium ore is too large, although the processing capacity of beryllium ore per single furnace crucible increases, the conversion rate of beryllium decreases and the recovery rate of beryllium decreases. If the proportion of beryllium ore is too small, the processing capacity of beryllium ore per single furnace crucible decreases, the production cost increases, and the impurity content increases during the subsequent leaching process. If the flux increases, the production cost is excessive and the impurity content increases during the subsequent leaching process. If the flux is too small, the conversion rate of beryllium decreases and the recovery rate of beryllium decreases. If the conductive agent is too much, the processing capacity of beryllium ore per single furnace crucible decreases and the production cost increases. If the conductive agent is too little, the melting time of a single furnace increases, the service life of the graphite crucible decreases, resulting in an increase in production cost.

[0025] In one preferred embodiment, the inert gas is nitrogen or argon.

[0026] In one preferred embodiment, the flow rate of the inert gas is 30 - 65 m 3 / h.

[0027] If the flow rate of the inert gas is too small, the oxygen content will increase and the crucible life will decrease. If it is too large, the inert gas is wasted and the production cost increases.

[0028] In one preferred embodiment, nitrogen displaces the air in the graphite crucible to control the oxygen concentration around the graphite crucible to be 50 - 1500 ppm.

[0029] Through the protective effect of nitrogen on the graphite crucible, the possibility of contact between the surface of the graphite crucible and oxygen is reduced, the reaction between C and O2 is eliminated, the life of the graphite crucible is extended, and the production cost is reduced.

[0030] In one preferred embodiment, the melting temperature of the medium and high frequency induction furnace is 1650 °C - 1850 °C, and the melting time t is 15 - 60 min.

[0031] If the temperature is too low and the time is too short, beryllium does not have enough time to react to form acid-soluble beryllium, and the conversion rate of beryllium decreases. If the temperature is too high and the time is too long, the power supply is wasted, the production cost increases, and the production capacity decreases.

[0032] A method for separating beryllium oxide includes the above melting process.

[0033] In one preferred embodiment, it further includes acid leaching, purification of the leaching solution, extraction of the purified solution, hydrolysis precipitation of the stripping solution, and calcination.

[0034] In one preferred embodiment, the extraction of the purified solution includes extraction, pickling, stripping, and regeneration.

[0035] The beneficial effects of the present invention are as follows:

[0036] (1) The method for smelting beryllium ore using a medium and high frequency induction furnace proposed by the present invention reduces the risk of beryllium poisoning for workers; at the same time, the power consumption and water consumption are significantly reduced, the number of furnace treatments of the crucible is increased by more than 30%, and the service life of the crucible is extended by more than 50%; the conversion rate of beryllium in the furnace charge is increased, the conversion rate of beryllium exceeds 99%, and the comprehensive recovery rate of beryllium is increased by more than 12% compared with the conventional sulfuric acid method for beryllium smelting.

[0037] (2) The present invention breaks the history of using electric arc furnaces to extract beryllium in beryllium smelting, innovatively uses a medium and high frequency induction furnace in the smelting process of beryllium ore, and successfully realizes the quality requirements of high-purity beryllium oxide products without adding purification steps for beryllium oxide.

[0038] (3) The present invention has the advantages of reasonable process, high beryllium recovery rate, low production cost, environmental protection, and no toxicity. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a process flow chart of the separation of beryllium oxide of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The present invention includes other embodiments and their modifications within the scope of its technical idea.

[0041] The embodiment of the present invention provides a method for separating beryllium oxide based on a medium and high frequency induction furnace, and the process flow chart is as Figure 1 shown. The present invention will be further described below through specific embodiments.

[0042] Example 1

[0043] As Figure 1 shown, a method for smelting beryllium ore using a medium and high frequency induction electric furnace includes the following steps:

[0044] The first step is crushing: crushing beryllium ore and limestone in a crusher to a particle size of 1 mm;

[0045] The second step is batching: mixing the crushed beryllium ore, limestone and graphite according to mass percentage concentrations of 1:0.65:0.05, 2:0.65:0.05, 1:0.30:0.05, 1:0.65:0.2 respectively, and stirring and mixing evenly, then adding them into the graphite crucible of the medium and high frequency induction electric furnace;

[0046] The third step is nitrogen protection: first use nitrogen with a purity of 99.5% and a flow rate of 30 m 3Replace the air in the graphite crucible with industrial nitrogen at a rate of [X] m³ / h, and control the oxygen concentration around the graphite crucible to 50 ppm;

[0047] The fourth step of smelting: When the oxygen concentration is 50 ppm, start the medium-high frequency induction furnace for smelting. The smelting frequency is 4500 Hz, the temperature is 1850 °C, and the smelting time t = 15 min.

[0048] Acidify and leach the beryllium glass produced after smelting → purify the leaching solution → extract the purified solution → hydrolyze and precipitate the stripping solution → beryllium hydroxide → calcination process (the same as the prior art CN202311202647.8), and obtain beryllium oxide products with 99.68%, 99.71%, 98.05% and 99.65% respectively. The recovery rates of beryllium reach 92%, 75%, 78% and 86% respectively. Among them, the components of beryllium ore, limestone and graphite added at a mass percentage concentration of 2:0.65:0.05 have incomplete melting phenomenon, and the crucible shows corrosion phenomenon.

[0049] Example 2

[0050] A method for smelting beryllium ore using a medium-high frequency induction furnace includes the following steps:

[0051] The first step of crushing: Crush beryllium ore and limestone in a crusher to a particle size of 1 mm;

[0052] The second step of batching: Batch the crushed beryllium ore, limestone and graphite according to the mass percentage concentration = 1:0.65:0.05, stir and mix evenly, and add them into the graphite crucible of the medium-high frequency induction furnace;

[0053] The third step of nitrogen protection: First, use industrial nitrogen with a purity of 99.5% and a flow rate of 10, 30, 70 m 3 / h to replace the air in the graphite crucible, and the oxygen concentrations around the graphite crucible are shown as 1200 ppm, 50 ppm and 3 ppm respectively;

[0054] The fourth step of smelting: When the oxygen concentrations are shown as 1200 ppm, 50 ppm and 3 ppm respectively, start the medium-high frequency induction furnace for smelting. The smelting frequency is 4500 Hz, the temperature is 1850 °C, and the smelting time t = 15 min.

[0055] Acidify and leach the beryllium glass produced after smelting → purify the leaching solution → extract the purified solution → hydrolyze and precipitate the stripping solution → beryllium hydroxide → calcination process to obtain a beryllium oxide product of about 99.69%, and the recovery rate of beryllium is about 90%. When the flow rate is 10 m 3 / h, the crucible is damaged by burning. When the flow rate is 70 m 3 / h, the crucible does not show any burning damage at all, but the gas consumption is too large. Therefore, consider the economic cost and choose the intermediate flow rate.

[0056] Example 3

[0057] A method for smelting beryllium ore using a medium and high frequency induction furnace includes the following steps:

[0058] The first step is crushing: crushing beryllium ore and limestone in a crusher to a particle size of 1 mm;

[0059] The second step is batching: proportioning the crushed beryllium ore, limestone and graphite according to the mass percentage concentration = 1:0.65:0.05, stirring and mixing evenly, and adding them into the graphite crucible of the medium and high frequency induction furnace;

[0060] The third step is nitrogen protection: first, replacing the air in the graphite crucible with industrial nitrogen with a purity of 99.5% and a flow rate of 30 m 3 / h, and controlling the oxygen concentration around the graphite crucible to 50 ppm;

[0061] The fourth step is smelting: when the oxygen concentration is 50 ppm, turn on the medium and high frequency induction furnace for smelting. The smelting frequency is 4500 Hz, the temperature is 1500, 1850, 2000 °C, and the smelting time t = 15 min.

[0062] The beryllium glass produced after smelting is acidified and leached → the leaching solution is purified → the purified solution is extracted → the hydrolytic precipitation of the stripping solution → beryllium hydroxide → calcination process to obtain beryllium oxide products at about 99.72%. The recovery rates of beryllium are 60%, 91% and 90.5% respectively. The previous smelting temperature significantly reduces the beryllium recovery rate, and the latter has no obvious effect on the beryllium recovery rate, but the energy consumption increases and the crucible shows signs of burning. Considering comprehensively, the intermediate smelting temperature is selected.

[0063] Example 4

[0064] A method for smelting beryllium ore using a medium and high frequency induction furnace includes the following steps:

[0065] The first step is crushing: crushing beryllium ore and calcite in a crusher to a particle size of 250 mm;

[0066] The second step is batching: proportioning the crushed beryllium ore, calcite and activated carbon according to the mass percentage concentration = 1:0.45:0.10, stirring and mixing evenly, and adding them into the graphite crucible of the medium and high frequency induction furnace;

[0067] The third step is nitrogen protection: first, replacing the air in the graphite crucible with industrial nitrogen with a purity of 99.1% and a flow rate of 65 m 3 / h, and controlling the oxygen concentration around the graphite crucible to 1500 ppm;

[0068] Fourth step of smelting: When the oxygen concentration is 1500 ppm, turn on the medium and high frequency induction furnace for smelting. The smelting frequency is 20000 Hz, the temperature is 1650 °C, and the smelting time t = 60 min.

[0069] The beryllium glass produced after smelting is acidified and leached → the leaching solution is purified → the purified solution is extracted → the hydrolysis precipitation of the stripping solution → beryllium hydroxide → calcination process is carried out to obtain a 99.75% beryllium oxide product, and the recovery rate of beryllium reaches 88%.

[0070] Example 5

[0071] A method for smelting beryllium ore using a medium and high frequency induction furnace includes the following steps:

[0072] First step of crushing: Crush beryllium ore and calcite in a crusher to a particle size of 250 mm;

[0073] Second step of batching: Batch the crushed beryllium ore and calcite according to a mass percentage concentration = 1:0.45, stir and mix evenly, and add them to the graphite crucible of the medium and high frequency induction furnace;

[0074] Third step of nitrogen protection: First, displace the air in the graphite crucible with industrial nitrogen with a purity of 99.1% and a flow rate of 65 m3 / h, and control the oxygen concentration around the graphite crucible to 1500 ppm;

[0075] Fourth step of smelting: When the oxygen concentration is 1500 ppm, turn on the medium and high frequency induction furnace for smelting. The smelting frequency is 20000 Hz, the temperature is 1650 °C, and the smelting time t = 60 min.

[0076] The beryllium glass produced after smelting is acidified and leached → the leaching solution is purified → the purified solution is extracted → the hydrolysis precipitation of the stripping solution → beryllium hydroxide → calcination process is carried out to obtain a 99.66% beryllium oxide product, and the recovery rate of beryllium without adding activated carbon reaches 69%.

[0077] Example 6

[0078] A method for smelting beryllium ore using a medium and high frequency induction furnace includes the following steps:

[0079] First step of crushing: Crush beryllium ore and calcite in a crusher to a particle size of 250 mm;

[0080] Second step of batching: Batch the crushed beryllium ore, calcite and activated carbon according to a mass percentage concentration = 1:0.45:0.10, stir and mix evenly, and add them to the graphite crucible of the medium and high frequency induction furnace;

[0081] Third step of nitrogen protection: Pass in air with a flow rate of 65 m3 / h;

[0082] Fourth step of smelting: When the oxygen concentration is 1500 ppm, start the medium and high frequency induction furnace for smelting. The smelting frequency is 20000 Hz, the temperature is 1650 °C, and the smelting time t = 60 min.

[0083] The beryllium glass produced after smelting is acid leached → the leaching solution is purified → the purified solution is extracted → the hydrolysis precipitation of the stripping solution → beryllium hydroxide → calcination process to obtain a 99.73% beryllium oxide product. The recovery rate of beryllium reaches 93%. There is an obvious burning loss phenomenon in the upper part of the crucible material without nitrogen protection, and the production life is reduced.

[0084] Example 7

[0085] A method for smelting beryllium ore using a medium and high frequency induction furnace includes the following steps:

[0086] First step of crushing: Crush beryllium ore and limestone in a crusher to a particle size of 150 mm;

[0087] Second step of batching: Batch the crushed beryllium ore, limestone and graphite according to the mass percentage concentration = 1:0.55:0.08, stir and mix evenly, and add them to the graphite crucible of the medium and high frequency induction furnace;

[0088] Third step of nitrogen protection: First, displace the air in the graphite crucible with industrial nitrogen with a purity of 99.95% and a flow rate of 50 m3 / h, and control the oxygen concentration around the graphite crucible to 500 ppm;

[0089] Fourth step of smelting: When the oxygen concentration is 500 ppm, start the medium and high frequency induction furnace for smelting. The smelting frequency is 8500 Hz, the temperature is 1750 °C, and the smelting time t = 35 min.

[0090] The beryllium glass produced after smelting is acid leached → the leaching solution is purified → the purified solution is extracted → the hydrolysis precipitation of the stripping solution → beryllium hydroxide → calcination process to obtain a 99.70% beryllium oxide product. The recovery rate of beryllium reaches 89%.

[0091] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A beryllium ore smelting process based on a medium and high frequency induction furnace, characterized in that, It includes the following steps: A. Crushing: Mix beryllium ore and flux and then crush them. The particle size of the crushed mixed material is controlled between 1 mm and 250 mm. B. Batching: Add a conductive agent to the mixed material. After mixing evenly, add it to a medium-high frequency induction furnace. Continuously introduce an inert gas during the smelting process and conduct smelting. Control the frequency of the medium-high frequency induction furnace to be between 4500 Hz and 20000 Hz. The flux is limestone or calcite; the conductive agent is graphite or activated carbon. The mass ratio of beryllium ore, flux and conductive agent is 1:0.45 - 0.65:0.05 - 0.

10. The flow rate of the inert gas is 30 - 65 m 3 / h; The smelting temperature of the medium-high frequency induction furnace is 1650 °C - 1850 °C. During the smelting process of the medium-high frequency induction furnace, the beryllium ore contacts the graphite crucible. The oxygen concentration around the graphite crucible is 50 - 1500 ppm. The smelting time of the high-frequency induction furnace is 15 - 60 min.

2. The beryllium ore smelting process according to claim 1, characterized in that, The particle size of the mixed material is controlled between 1 mm and 200 mm.

3. The beryllium ore smelting process according to claim 1, characterized in that, The inert gas is nitrogen or argon.

4. A method for separating beryllium oxide, characterized in that, It includes the smelting process described in any one of claims 1 - 3, and also includes acidification leaching of the beryllium glass produced after smelting, purification of the leaching solution, extraction of the purified solution, hydrolysis precipitation of the stripping solution, obtaining beryllium hydroxide, and calcination treatment.

5. The separation method according to claim 4, wherein The extraction of the purified solution includes extraction, pickling, stripping and regeneration.

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