Method for roasting beryllium-containing material by adopting mixed fuel

Abstract

The method for roasting the beryllium-containing material by adopting the mixed fuel comprises the following steps: I, mixing a beryllium-containing raw material with biomass to obtain a beryllium-containing mixture; and II, roasting the beryllium-containing mixture by adopting a mixed combustible gas comprising hydrogen and a combustion-supporting gas to obtain a roasted product. According to the method for roasting the beryllium-containing material by adopting the mixed fuel, the beryllium-containing material is roasted by utilizing the hydrogen and the combustion-supporting gas, so that the carbon emission is reduced. And meanwhile, in the decomposition process of the beryllium-containing material, C in biomass and generated CO are used for reducing BeO at a high temperature, so that part of elemental beryllium is generated in a roasted product, the efficiency of the subsequent elemental beryllium preparation process is improved, and the technological process is shortened.

Description

Technical Field

[0001] The invention relates to a method for roasting beryllium-containing materials, in particular to a method for roasting beryllium-containing materials by using mixed fuel, and belongs to the field of preparation of beryllium and its derivatives. Background Art

[0002] Calcination is a sulfuric acid process (such as Figure 3 The main reaction during the process is the thermal decomposition of Be(OH)2 and BeSO4. At present, coal, electricity or natural gas are often used for heating. The wet hydroxide beryllium is dried, calcined and cooled in a tunnel kiln / rotary kiln to obtain industrial beryllium oxide, accompanied by a large amount of CO2 emissions. Taking the currently commonly used natural gas roasting method as an example, to obtain the final BeO product, 1 mol of natural gas emits 1 mol of CO2, which has a large carbon emission.

[0003] Hydrogen energy is regarded as the cleanest energy with the greatest development potential in the 21st century. Due to its many advantages such as diverse sources, clean and low-carbon, flexible and efficient, and rich application scenarios, it has been included in the national energy strategic deployment of many countries. The 21st century is the hydrogen era. Hydrogen metallurgy is the reduction of hydrogen to water instead of carbon. It not only has no carbon emissions, but also has an extremely fast reaction speed. my country regards the establishment of an industrial revolution of "hydrogen economy" to replace fossil energy as an important strategic goal to achieve new industrialization and realize China's peaceful development. Using hydrogen for the beryllium industry is one of the future development directions. It is one of the effective ways for the beryllium industry to optimize its energy structure, process flow and industrial structure and achieve low-carbon, green and sustainable development.

[0004] In addition, the equations for the thermal decomposition of Be(OH)2 and BeSO4 are as follows: Be(OH)2→BeO+H2O BeSO4·Be(OH)2·xH2O→2BeO+SO3↑+(x+1)H2O Since the raw material contains about 24% adsorbed water and 27.86% crystal water, Be(OH)2 only accounts for 48.14%. According to the mass ratio, it can be inferred that each 1 mol of Be(OH)2 contains about 1.38 mol of crystal water, that is, the chemical formula of the raw material is Be(OH)2·1.38H2O. In terms of kinetics, the adsorbed water and crystal water need to be removed first, and then the thermal decomposition reaction of Be(OH)2 and BeSO4 at a higher temperature is conducive to improving the reaction efficiency. Among them, the adsorbed water is free outside the crystal and begins to volatilize at about 60°C, while the crystal water is within the unit cell and generally volatilizes at about 300°C. Summary of the invention

[0005] In view of the problem that in the prior art hydrogen-rich roasting process of Be(OH)2 and BeSO4, the hydrogen concentration needs to be controlled at all times during the reaction process, the present invention mixes the beryllium-containing raw material with biomass, and then provides fuel through hydrogen to provide heat for the reaction. After reaching the decomposition temperature, the beryllium-containing material including the biomass begins to decompose, and after the decomposition is completed, a roasting product containing beryllium oxide is obtained.

[0006] According to an embodiment of the present invention, a method for roasting a beryllium-containing material using mixed combustion is provided.

[0007] A method for roasting beryllium-containing materials using a mixed fuel, the method comprising the following steps: Step I: mixing the beryllium-containing raw material with biomass to obtain a beryllium-containing mixed material; Step II: using a mixed combustible gas including hydrogen and a combustion-supporting gas to roast the beryllium-containing mixture to obtain a roasted product.

[0008] Preferably, the beryllium-containing raw material includes Be(OH)2 and / or BeSO4.

[0009] Preferably, the biomass is a solid fuel composed of biomass.

[0010] Preferably, the mixing mass ratio of the biomass to the beryllium-containing raw material is 1% to 30%, preferably 15% to 25%.

[0011] Preferably, in the mixed combustible gas, the volume fraction of hydrogen is 4% to 30%, preferably 5% to 25%.

[0012] Preferably, the calcination temperature is 700-1200° C., preferably 900-1100° C., more preferably 995-1065° C. The calcination time is 1-6 hours, preferably 2-4 hours.

[0013] Preferably, the method further comprises: a pre-step a: The beryllium-containing raw material is pretreated; the pretreatment is preheating the beryllium-containing raw material, and then mixing the preheated beryllium-containing raw material with biomass.

[0014] Preferably, the preheating temperature is 300° C. to 600° C., and the preheating time is 1 to 8 hours.

[0015] Preferably, the moisture content of the beryllium-containing raw material after pretreatment is less than 3%, preferably less than 1%.

[0016] Preferably, the preheating is a two-stage preheating; wherein the temperature of the first preheating stage is not less than 60°C, preferably 80-150°C; the time of the first preheating stage is 0.1h-2h, preferably 0.3h-1.5h; the temperature of the second preheating stage is not less than 300°C, preferably 450°C-600°C; the time of the second preheating stage is 0.8h-5h, preferably 1.5-3h.

[0017] Preferably, the method further comprises: a pre-step b: pre-treating the biomass: washing the biomass with water; the water washing temperature is 70-95°C, the water washing time is 10-80 min, and the water washing liquid-solid ratio is 20-160 ml / g; preferably, the water washing temperature is 75-90°C, the water washing time is 10-40 min, and the water washing liquid-solid ratio is 40-80 ml / g.

[0018] Preferably, the particle size of the beryllium-containing material is less than 1 mm, preferably less than 0.3 mm.

[0019] Preferably, the method further comprises: step III: reducing the obtained roasting product to prepare elemental beryllium; Preferably, the method for reducing the obtained calcined product is any one of magnesium thermal reduction, carbon thermal reduction and molten salt electrolysis.

[0020] In the present invention, a beryllium-containing material is mixed with biomass, and then the beryllium-containing mixture is placed in a mixed atmosphere of hydrogen and combustion-supporting gas for roasting, and a roasting product is obtained after the roasting is completed. The beryllium-containing material is roasted with hydrogen and oxygen-containing gas to reduce carbon emissions. In addition, since beryllium is an important chemical element with a variety of unique physical and chemical properties, it has shown an irreplaceable role in multiple fields (such as aerospace, atomic reactors, metallurgical industry, electronics industry, etc.), so the current demand for elemental Be is relatively high. The main component of the roasting product is BeO, and it needs to be further reduced to obtain elemental beryllium. In the present invention, biomass is added during the decomposition process of the beryllium-containing material, and BeO is reduced at high temperature using C and CO, so that part of the elemental beryllium is generated in the roasting product, which is beneficial to improve the efficiency of subsequent processes and shorten the process flow.

[0021] In the present invention, the mixing mass ratio of biomass and beryllium-containing raw materials is limited. Studies have shown that the best reduction effect is achieved when the mass ratio of biomass to beryllium-containing raw materials is 15% to 25% (e.g., 15%, 16%, 18%, 19%, 20%, 22%, 24%, 25%). If the biomass is too little, the ideal reduction effect cannot be achieved. If the biomass is too much, the temperature of the decomposition process of the beryllium-containing material may be affected, resulting in reduced reaction efficiency and increased carbon emissions.

[0022] In the present invention, the Gibbs free energy ΔG of the decomposition reaction of Be(OH)2 and BeSO4 decreases sharply with the increase of reaction temperature. When the temperature is higher than 80°C, ΔG is less than 0, indicating that the decomposition reaction of Be(OH)2 can proceed spontaneously at a temperature higher than 80°C. In addition, the decomposition reaction of Be(OH)2 is an endothermic reaction. The increase in temperature is conducive to the forward reaction, and the amount of heat absorbed decreases with the increase in temperature. As the temperature increases, the reaction equilibrium constant K sp It increases first and then decreases, and reaches a maximum value at around 1040℃, indicating that the degree of decomposition reaction of Be(OH)2 increases first and then decreases with the increase of temperature, and the degree of reaction is the largest at around 1040℃. sp >105, indicating that the reaction is relatively complete within this temperature range. Therefore, the present invention controls the calcination temperature between 700 and 1200°C (e.g., 710°C, 730°C, 750°C, 780°C, 800°C, 820°C, 850°C, 870°C, 900°C, 905°C, 915°C, 930°C, 950°C, 960°C, 980°C, 1000°C, 1020°C, 1040°C, 1050°C, 1060°C, 1065°C, 1080°C, 1100°C, 1120°C, 1140°C, 1160°C, 1180°C), so that the reaction is within the optimal reaction temperature range, which is conducive to the forward reaction and improves the reaction process of Be(OH)2.

[0023] In the present invention, the beryllium-containing raw material is further preheated to reduce the free water and crystal water content in the beryllium-containing raw material, which is conducive to the forward decomposition reaction and improves the reaction efficiency during the decomposition process. Preferably, the beryllium-containing raw material is preheated in two stages, and the preheating temperature and preheating time are limited to minimize the water content in the beryllium-containing raw material while avoiding fuel waste, and preventing water evaporation during the roasting process from affecting the reaction process.

[0024] In the present invention, the biomass can also be pretreated, and the temperature, time and liquid-to-solid ratio of the biomass water washing are limited, so as to increase the content of effective components in the biomass and improve the yield of the biomass water washing product.

[0025] In the present invention, the method for reducing beryllium oxide to elemental beryllium can be magnesium thermal reduction, carbon thermal reduction, and molten salt electrolysis (all of which are prior arts). For example, magnesium thermal reduction is to reduce beryllium oxide with magnesium at 1000-1600° C. to obtain magnesium oxide and elemental beryllium.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a method for roasting beryllium-containing materials using a mixed fuel, which uses hydrogen and combustion-supporting gas to roast the beryllium-containing materials, thereby reducing carbon emissions. At the same time, during the decomposition of the beryllium-containing materials, the C in the biomass and the generated CO are used to reduce BeO at high temperature, so that part of the elemental beryllium is generated in the roasting product, which is beneficial to improving the efficiency of the subsequent process for preparing elemental beryllium and shortening the process flow.

[0027] 2. The present invention provides a method for roasting beryllium-containing materials using mixed fuels, which limits parameters such as biomass mass, hydrogen gas volume fraction, and roasting temperature, so that the beryllium-containing materials can be fully decomposed while the obtained beryllium oxide can be reduced as much as possible, thereby improving product purity and reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the SEM image of the calcined product in Example 1.

[0029] Figure 2 This is the SEM image of the beryllium-containing raw material in Example 1.

[0030] Figure 3 The figure is a process diagram for preparing beryllium oxide by the sulfuric acid process in the prior art. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments. Example 1

[0032] A method for roasting beryllium-containing materials using a mixed fuel, the method comprising the following steps: a Pretreatment of the beryllium-containing raw material: preheat 50 kg of the beryllium-containing raw material at 100°C for 1 hour, and then preheat at 500°C for 2 hours to obtain 23.03 kg of pretreated Be(OH)2; wherein the mass of beryllium hydroxide in the beryllium-containing raw material is about 45.7%, the water content of the beryllium-containing raw material is 54.3%, and the water content of the treated beryllium-containing raw material is about 0.78%.

[0033] b Pre-treating the biomass: 10 kg of biomass was placed at 80° C. and washed with 600 L of water for 30 min to obtain 7 kg of pre-treated biomass.

[0034] Step I: 4.6 kg of biomass is mixed with 23.03 kg of pretreated beryllium-containing raw material to obtain 28.03 kg of beryllium-containing mixed material.

[0035] Step II: The beryllium-containing mixture is roasted using a mixed combustible gas of hydrogen and air to obtain 9.53 kg of roasted products. Among them, the volume fraction of hydrogen in the mixed combustible gas is 15.0%. The roasting temperature is 1030°C and the roasting time is 3 hours. It is detected that the decomposition rate of beryllium hydroxide in the roasted product is 96.1%, and the mass percentage of elemental beryllium is 24.3% (accounting for 48.5% of the total mass of beryllium).

[0036] Step III: react the obtained calcined product with 14.98 kg of magnesium at 1500° C. for 5 hours to obtain 4.93 kg of elemental beryllium, wherein the purity of the elemental beryllium is 96.5%.

[0037] Example 1 was repeated, except that the parameters in the experimental process were changed to conduct a single variable experiment. The specific parameters are shown in Table 1.

[0038] Table 1 Experimental parameters of each embodiment

[0039] The product obtained from the above experiment was tested, and the results are shown in Table 2.

[0040] Table 2 Test results of the products of each example

[0041] The decomposition rate of beryllium hydroxide is obtained by dividing the total mass of beryllium in beryllium oxide and elemental beryllium in the calcined product obtained in step II by the mass of beryllium in the beryllium-containing raw material.

Claims

1. A method for roasting beryllium-containing materials using a mixed fuel, characterized in that: The method comprises the following steps: Step I: mixing the beryllium-containing raw material with biomass to obtain a beryllium-containing mixed material; Step II: using a mixed combustible gas including hydrogen and a combustion-supporting gas to roast the beryllium-containing mixture to obtain a roasted product.

2. The method according to claim 1, characterized in that: The beryllium-containing raw material is Be(OH)2 and / or BeSO4; and / or The biomass is a solid fuel composed of biomass; and / or The mixing mass ratio of the biomass to the beryllium-containing raw material is 1% to 30%, preferably 15% to 25%.

3. The method according to claim 2, characterized in that: In the mixed combustible gas, the volume fraction of hydrogen is 4% to 30%, preferably 5% to 25%.

4. The method according to any one of claims 1 to 3, characterized in that: The calcination temperature is 700-1200° C., preferably 900-1100° C., more preferably 995-1065° C.; the calcination time is 1-6 hours, preferably 2-4 hours.

5. The method according to any one of claims 1 to 4, characterized in that: The method further comprises: a pre-step a: The beryllium-containing raw material is pretreated; the pretreatment is preheating the beryllium-containing raw material, and then mixing the preheated beryllium-containing raw material with biomass.

6. The method according to claim 5, characterized in that: The preheating temperature is 300℃~600℃, and the preheating time is 1~8h; Preferably, the moisture content of the beryllium-containing raw material after pretreatment is less than 3%, preferably less than 1%.

7. The method according to claim 5 or 6, characterized in that: The preheating is a two-stage preheating; wherein the temperature of the first stage preheating is not less than 60°C, preferably 80-150°C; the time of the first stage preheating is 0.1h-2h, preferably 0.3h-1.5h; the temperature of the second stage preheating is not less than 300°C, preferably 450°C-600°C; the time of the second stage preheating is 0.8h-5h, preferably 1.5-3h.

8. The method according to any one of claims 1 to 7, characterized in that: The method also includes: a pre-step b: pre-treating the biomass: washing the biomass with water; the water washing temperature is 70-95°C, the water washing time is 10-80 minutes, and the water washing liquid-solid ratio is 20-160 ml / g; preferably, the water washing temperature is 75-90°C, the water washing time is 10-40 minutes, and the water washing liquid-solid ratio is 40-80 ml / g.

9. The method according to any one of claims 1 to 8, characterized in that: The particle size of the beryllium-containing material is less than 1 mm, preferably less than 0.3 mm.

10. The method according to any one of claims 1 to 9, characterized in that: The method further comprises: step III: reducing the obtained roasting product to prepare elemental beryllium; Preferably, the method for reducing the obtained calcined product is any one of magnesium thermal reduction, carbon thermal reduction and molten salt electrolysis.

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