Recovery and purification process of ammonium bifluoride from spent nitrogen trifluoride electrolyte

Abstract

The present invention belongs to the technical field of the recovery and purification process of fluorine chemical industry, and specifically relates to the recovery and purification process of ammonium bifluoride in nitrogen trifluoride waste electrolyte. The recovery and purification process of ammonium bifluoride in the described nitrogen trifluoride waste electrolyte: the nitrogen trifluoride waste residue is crushed and dissolved, the temperature is controlled to be 60°C-70°C, ammonia is introduced to adjust the pH to 4.5-5, the filtrate is taken after filter pressing, potassium carbonate is added to adjust the pH to 9-10, and the filtrate after filter pressing is crystallized, centrifuged, and dried to obtain pure ammonium bifluoride. Only ammonia can be introduced, and it cannot be adjusted by adding ammonia water, and the addition of ammonia water cannot remove excess water. The mass proportion of ammonium bifluoride in the described nitrogen trifluoride waste residue is 40%-45%. The present invention provides a recovery and purification process for the problem of low quality of the obtained product when wet recovery is used in the treatment process of nitrogen trifluoride waste electrolyte, and the recovered ammonium bifluoride has high purity, high yield, and green, environmentally friendly and safe recovery process.

Description

Technical Field

[0001] The invention belongs to the technical field of recovery and purification technology of fluorine chemical industry, and specifically relates to a recovery and purification technology of ammonium bifluoride in nitrogen trifluoride waste electrolyte. Background Art

[0002] Electronic nitrogen trifluoride is mainly used in the fields of new materials (fine and special chemicals) and ultra-clean high-purity electronic gases. NF3 has excellent etching rate and selectivity, and does not leave any residual substances on the surface of the etched object. It is widely used in circuit board etching, LCD screen etching and cleaning, chip manufacturing, high-energy lasers and other industries. It is an excellent plasma etching gas and a very good cleaning agent in the electronics industry. However, the treatment of nitrogen trifluoride electrolytic waste slag is a problem of concern in the industry. At present, there are two ways to treat nitrogen trifluoride electrolytic waste slag: pyrometallurgical recovery and wet recovery. Nitrogen trifluoride manufacturers entrust qualified hazardous waste treatment manufacturers to recover nickel in pyrometallurgy, and ammonium bifluoride is treated by high-temperature incineration. This method is more corrosive to the equipment, and ammonium bifluoride cannot be recovered. The industry prefers wet recovery, that is, after the nickel slag is separated from ammonium bifluoride, the nickel slag is recovered by wet smelting, and ammonium bifluoride is recovered by dissolution, crystallization, and drying. However, the quality of ammonium bifluoride products recovered by the current recovery process is low.

[0003] The patent CN118147661A proposes a method for recycling and reusing waste electrolyte from a nitrogen trifluoride electrolytic cell. The method uses ammonium sulfide to remove nickel, but cannot effectively remove nickel by breaking the complex. At the same time, ammonium sulfide is easy to generate hydrogen sulfide in an acidic environment (the waste electrolyte solution of the electrolytic cell is acidic), which is dangerous. At the same time, this method cannot solve the problem of fluorosilicate impurities in ammonium bifluoride, and the quality of the recovered ammonium bifluoride cannot meet the needs of electrolysis of nitrogen trifluoride. Summary of the invention

[0004] The technical problem to be solved by the present invention is the problem of low product quality when wet recovery is adopted in the existing treatment process of nitrogen trifluoride waste electrolyte. The present invention provides a recovery and purification process of ammonium bifluoride in nitrogen trifluoride waste electrolyte. The recovered ammonium bifluoride has high purity and high yield, and the recovery process is green, environmentally friendly and safe.

[0005] The recovery and purification process of ammonium bifluoride in nitrogen trifluoride waste electrolyte of the present invention comprises the following steps: crushing and dissolving nitrogen trifluoride waste residue, controlling the temperature to 60°C-70°C, introducing ammonia gas to adjust the pH value to 4.5-5, taking the filtrate after filter pressing, adding potassium carbonate to adjust the pH value to 9-10, crystallizing, centrifuging and drying the filtrate after filter pressing to obtain pure ammonium bifluoride. Only ammonia gas can be introduced, and it is impossible to adjust by adding ammonia water, and adding ammonia water cannot remove excess water.

[0006] The mass proportion of ammonium bifluoride in the nitrogen trifluoride waste residue is 40%-45%.

[0007] The mass proportion of ammonium bifluoride in the nitrogen trifluoride waste residue is 40%-45%, the mass proportion of nickel element is 2.5%-3.5%, the mass proportion of nickel fluoride ammonia complex is 28%-32%, the mass proportion of copper fluoride ammonia complex is 2%-3%, the mass proportion of iron fluoride is 8%-10%, the mass proportion of water is 2%-3%, and the balance is fluorosilicate.

[0008] The nitrogen trifluoride waste residue is crushed to an average particle size of 0.8-1.2 cm.

[0009] The nitrogen trifluoride waste residue is crushed and dissolved in water, with the mass ratio of water to nitrogen trifluoride waste residue being 4:1-5:1.

[0010] The potassium carbonate added is potassium carbonate solid or potassium carbonate solution with a mass concentration of 10%-40%. The pH can only be adjusted by potassium carbonate, and cannot be adjusted by sodium carbonate, because sodium carbonate cannot remove the fluorosilicate ions therein, and the solubility of sodium fluoride is low, which will form sodium fluoride precipitation.

[0011] When introducing ammonia gas, stir at a speed of 40 rpm-50 rpm. After the introduction is completed, continue stirring to react for 2h-3h.

[0012] When adding potassium carbonate, stir at a speed of 40 rpm-50 rpm. After the addition is completed, continue stirring and reacting for 3h-4h.

[0013] Potassium carbonate is added to adjust the pH to 9-10. The nickel-ammine complex is broken to form nickel hydroxide precipitate. The fluorosilicates in the solution also form potassium fluorosilicate precipitate with lower solubility, which is then filtered and the filter mud after filtering is used to recover nickel.

[0014] Potassium carbonate was added to adjust the pH to 9-10, and the filtrate after filter pressing was subjected to single-effect concentration. When the mass concentration of ammonium bifluoride reached 25%, filter pressing was performed, and the filtrate after filter pressing was subjected to crystallization reaction at 0-5°C for 4-6h.

[0015] Specifically, the recovery and purification process of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is as follows: first, the nitrogen trifluoride waste residue is crushed to an average particle size of 0.8-1.2 cm, added to a dissolving kettle, and water is added to dissolve according to a mass ratio of water to nitrogen trifluoride waste residue of 4:1-5:1, the temperature is controlled at 60°C-70°C, ammonia is introduced to adjust the pH to 4.5-5, and the mixture is stirred at a speed of 40 rpm-50 rpm. After the introduction, the mixture is stirred for 2h-3h, and then the mixture is pressed into a filter press by a delivery pump for filtration. The primary filter mud is a nickel-containing material, and nickel is further recovered or sold. The primary filtrate after filtration is pumped into a decontamination tank by a pump, and an appropriate amount of potassium carbonate solid or a potassium carbonate solution with a mass concentration of 10%-40% is added to adjust the pH to 9-10, stirring at a speed of 40 rpm-50 rpm, continuing to stir and react for 3h-4h after the addition is completed, and then pressing it into a filter press through a delivery pump for filter press separation. The secondary filter mud is a mixture of potassium fluoride silicate and nickel hydroxide, which is sold or further nickel recovered. The secondary filtrate after filter press is stored in a filtrate tank, and then pumped into a single-effect evaporation system by a delivery pump for single-effect concentration. When the mass concentration of ammonium bifluoride reaches 25%, the material is placed in a crystallization kettle at 0℃-5℃ for crystallization. After reacting for 4h-6h, the material is placed in a centrifuge for centrifugation. After centrifugation, the crystallized material enters a dryer for drying, and the centrifuge returns to the single-effect evaporation system for continued concentration. After the material is sampled and tested after passing the test, the obtained pure ammonium bifluoride is packaged and stored.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The process for recovering and purifying ammonium bifluoride from nitrogen trifluoride waste electrolyte of the present invention significantly improves the recovery quality and yield of ammonium bifluoride.

[0018] (2) The present invention effectively solves the problem of low product quality in the traditional wet recovery process by precisely controlling the reaction conditions and steps. Ammonia gas is used to accurately adjust the pH value to avoid residual water. Potassium carbonate is used to accurately control the pH of the solution, effectively removing impurities such as fluorosilicate and ensuring the high purity of ammonium bifluoride.

[0019] (3) The present invention also achieves the recycling of valuable metals such as nickel, further improving the economy and environmental friendliness of the process. The entire recycling process is green, environmentally friendly and safe, providing a new efficient and environmentally friendly way for the treatment of nitrogen trifluoride waste electrolyte. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments.

[0021] The nitrogen trifluoride electrolysis waste slag described in the following examples and comparative examples is the waste slag obtained by the normal process electrolysis process. The nitrogen trifluoride waste slag contains 40%-45% ammonium bifluoride by mass, 2.5%-3.5% nickel by mass, 28%-32% nickel fluoride ammonia complex, 2%-3% copper fluoride ammonia complex, 8%-10% iron fluoride, 2%-3% water, and the balance is fluorosilicate.

[0022] Example 1

[0023] In this embodiment, the mass proportion of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is 40%.

[0024] The recovery and purification process of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is as follows: first, the nitrogen trifluoride waste residue is crushed to an average particle size of 1.0 cm, and then added to a dissolving kettle, water is added to dissolve according to a mass ratio of water to nitrogen trifluoride waste residue of 4:1, the temperature is controlled to be 65°C, ammonia is introduced to adjust the pH to 4.5, stirring at a speed of 40 rpm, and stirring and reacting for 3 hours after the introduction is completed, and then the mixture is pressed into a filter press by a delivery pump for pressure filtration, and the primary filter mud is a nickel-containing material, and nickel is continued to be recovered; the primary filtrate after the pressure filtration is pumped into a decontamination tank, potassium carbonate solid is added to adjust the pH to 10, and stirring is carried out at a speed of 40 rpm. After the addition is completed, stirring and reacting for 4 hours, and then Then it is pressed into the filter press by a delivery pump for pressure filtration separation. The secondary filter mud is a mixture of potassium fluoride silicate and nickel hydroxide, and nickel is further recovered. The secondary filtrate after pressure filtration is stored in the filtrate tank, and then pumped into the single-effect evaporation system by a delivery pump for single-effect concentration. When the mass concentration of ammonium bifluoride reaches 25%, the material is placed in a crystallization kettle and cooled to 2°C for crystallization. After reacting for 5 hours, the material is placed in a centrifuge for centrifugation. After centrifugation, the crystallized material enters the dryer for drying, and the centrifuge liquid returns to the single-effect evaporation system for further concentration. After drying, the material is sampled for testing. According to GB / T28655-2012, the content is detected to be 98.1%. The obtained pure ammonium bifluoride is packaged and stored, and its yield is calculated to be 96.5%.

[0025] The primary and secondary filter muds were acidified, iron removed, copper removed and extracted to obtain pure nickel sulfate electroplating solution. The nickel sulfate electroplating solution was further electroplated to prepare nickel plates to obtain nickel with a purity of 99.82% and a nickel recovery rate of 89%.

[0026] Example 2

[0027] In this embodiment, the mass proportion of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is 40%.

[0028] The recovery and purification process of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is as follows: first, the nitrogen trifluoride waste residue is crushed to an average particle size of 1.2 cm, and then added to a dissolving kettle, water is added to dissolve according to a mass ratio of water to nitrogen trifluoride waste residue of 5:1, the temperature is controlled to be 60°C, ammonia is introduced to adjust the pH to 5, stirring at a speed of 40 rpm, and stirring and reacting for 3 hours after the introduction is completed, and then the mixture is pressed into a filter press by a delivery pump for pressure filtration, and the primary filter mud is a nickel-containing material, and nickel is continued to be recovered; the primary filtrate after the pressure filtration is pumped into a decontamination tank, a potassium carbonate solution with a mass concentration of 40% is added to adjust the pH to 9, and stirring is carried out at a speed of 40 rpm. After the addition is completed, stirring and reacting for 4 hours h, and then it is pressed into the filter press by a delivery pump for pressure filtration separation. The secondary filter mud is a mixture of potassium fluoride silicate and nickel hydroxide, and nickel is further recovered. The secondary filtrate after pressure filtration is stored in the filtrate tank, and then it is pumped into the single-effect evaporation system by a delivery pump for single-effect concentration. When the mass concentration of ammonium bifluoride reaches 25%, the material is placed in a crystallization kettle to cool and crystallize at 0°C. After reacting for 6 hours, the material is placed in a centrifuge for centrifugation. After centrifugation, the crystallized material enters the dryer for drying, and the centrifuge liquid returns to the single-effect evaporation system for further concentration. After drying, the material is sampled for testing. According to GB / T28655-2012, the content is detected to be 97.8%. The obtained pure ammonium bifluoride is packaged and stored, and its yield is calculated to be 95.8%.

[0029] The primary and secondary filter muds were acidified, iron removed, copper removed and extracted to obtain pure nickel sulfate electroplating solution. The nickel sulfate electroplating solution was further electroplated to prepare nickel plates to obtain nickel with a purity of 99.88% and a nickel recovery rate of 88%.

[0030] Example 3

[0031] In this embodiment, the mass proportion of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is 45%.

[0032] The recovery and purification process of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is as follows: first, the nitrogen trifluoride waste residue is crushed to an average particle size of 0.8 cm, water is added to dissolve it according to the mass ratio of water to nitrogen trifluoride waste residue of 4:1, the temperature is controlled to 70°C, ammonia is introduced to adjust the pH to 5, stirring is carried out at a speed of 50 rpm, and stirring and reacting is continued for 2 hours after the introduction is completed, and then it is pressed into a filter press by a delivery pump for pressure filtration. The primary filter mud is a nickel-containing material, and nickel is continued to be recovered; the primary filtrate after the pressure filtration is pumped into a decontamination tank, and a potassium carbonate solution with a mass concentration of 10% is added to adjust the pH to 10, and stirring is carried out at a speed of 50 rpm. After the addition is completed, stirring and reacting is continued for 3 hours, and then by The delivery pump is pressed into the filter press for pressure filtration separation. The secondary filter mud is a mixture of potassium fluoride silicate and nickel hydroxide, and nickel is further recovered. The secondary filtrate after pressure filtration is stored in the filtrate tank, and then pumped into the single-effect evaporation system by the delivery pump for single-effect concentration. When the mass concentration of ammonium bifluoride reaches 25%, the material is placed in a crystallization kettle to cool and crystallize at 5°C. After reacting for 4 hours, the material is placed in a centrifuge for centrifugation. After centrifugation, the crystallized material enters the dryer for drying, and the centrifuge liquid returns to the single-effect evaporation system for further concentration. After the material is dried, the sample is tested and qualified. According to GB / T28655-2012, the content is detected to be 97.6%. The obtained pure ammonium bifluoride is packaged and stored, and the yield is calculated to be 95.3%.

[0033] The primary and secondary filter muds were acidified, iron removed, copper removed and extracted to obtain pure nickel sulfate electroplating solution. The nickel sulfate electroplating solution was further electroplated to prepare nickel plates to obtain nickel with a purity of 99.82% and a nickel recovery rate of 86%.

[0034] Example 4

[0035] In this embodiment, the mass proportion of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is 45%.

[0036] The recovery and purification process of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is as follows: first, the nitrogen trifluoride waste residue is crushed to an average particle size of 1.0 cm, water is added to dissolve it according to the mass ratio of water to nitrogen trifluoride waste residue of 4:1, the temperature is controlled to 60°C, ammonia is introduced to adjust the pH to 5, stirring is carried out at a speed of 45 rpm, and stirring and reacting is continued for 2 hours after the introduction is completed, and then it is pressed into a filter press by a delivery pump for pressure filtration. The primary filter mud is a nickel-containing material, and nickel is continued to be recovered; the primary filtrate after the pressure filtration is pumped into a decontamination tank, and a potassium carbonate solution with a mass concentration of 20% is added to adjust the pH to 10, and stirring is carried out at a speed of 45 rpm. After the addition is completed, the stirring reaction is continued for 3 hours, and then by The delivery pump is pressed into the filter press for pressure filtration separation. The secondary filter mud is a mixture of potassium fluoride silicate and nickel hydroxide, and nickel is further recovered. The secondary filtrate after pressure filtration is stored in the filtrate tank, and then pumped into the single-effect evaporation system by the delivery pump for single-effect concentration. When the mass concentration of ammonium bifluoride reaches 25%, the material is placed in a crystallization kettle to cool and crystallize at 0°C. After reacting for 6 hours, the material is placed in a centrifuge for centrifugation. After centrifugation, the crystallized material enters the dryer for drying, and the centrifuge liquid returns to the single-effect evaporation system for further concentration. After the material is dried, the sample is tested and qualified. According to GB / T28655-2012, the content is detected to be 97.7%. The obtained pure ammonium bifluoride is packaged and stored, and the yield is calculated to be 95.9%.

[0037] The primary and secondary filter muds were acidified, iron removed, copper removed and extracted to obtain pure nickel sulfate electroplating solution. The nickel sulfate electroplating solution was further electroplated to prepare nickel plates to obtain nickel with a purity of 99.88% and a nickel recovery rate of 86%.

[0038] Comparative Example 1

[0039] This comparative example is the same as Example 1, except that "adding solid potassium carbonate to adjust pH to 10" is replaced by "adding solid sodium carbonate to adjust pH to 10", and the other preparations are the same. However, no ammonium bifluoride product is obtained, because after adding solid sodium carbonate, the pH can reach 10, which has the effect of further removing nickel, but sodium ions combine with fluoride ions to form sodium fluoride precipitates with low solubility, affecting the yield, and the solubility of sodium fluorosilicate is much higher than that of potassium fluorosilicate, and fluorosilicate ions cannot be removed, but sodium ions are brought in, so high-purity ammonium bifluoride products cannot be obtained, and the purity of the obtained ammonium bifluoride is 88%.

[0040] Comparative Example 2

[0041] In this comparative example, the mass proportion of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is 40%.

[0042] The nitrogen trifluoride waste residue was crushed to an average particle size of 1.2 cm, added to a dissolving kettle, and water was added to dissolve it according to a mass ratio of water to nitrogen trifluoride waste residue of 5:1. The temperature was controlled to 60°C, and ammonia was continuously introduced to adjust the pH to 10. The mixture was stirred at a speed of 40 rpm. After the introduction was completed, the stirring reaction was continued for 3 hours. Then, the mixture was pressed into a filter press by a delivery pump for pressure filtration. The primary filter mud was a nickel-containing material, and the yield was reduced by 90% compared with that in Example 1. The filter mud was mainly nickel element, indicating that the ionic nickel was not precipitated. The primary filtrate after pressure filtration was dark blue and had a strong pungent smell of ammonia, indicating that the nickel ions were first precipitated and then dissolved with the gradual addition of ammonia, and the excess ammonia could not precipitate the ionic nickel. The filtrate was pumped into a de-impurity tank, and an appropriate amount of potassium carbonate solution with a mass concentration of 40% was added because the pH reached the required value, and the mixture was stirred at a speed of 40 rpm. After the addition was completed, the mixture was stirred and reacted for 4 hours, and then the mixture was pressed into a filter press by a delivery pump for pressure filtration separation. The yield of the secondary filter mud increased by 10% compared with that in Example 1, and the mixture was mainly a mixture containing nickel hydroxide and potassium fluorosilicate, and nickel was further recovered. The total output of the primary and secondary filter muds decreased by 85% compared with that in Example 1, and most of the nickel ions did not settle. The secondary filtrate after filter pressing is still blue and stored in the filtrate tank. It is then pumped into the single-effect evaporation system by a delivery pump for single-effect concentration. When the mass concentration reaches 25%, the material is placed in a crystallization kettle for cooling and crystallization at 0°C. After 6 hours of reaction, the material is placed in a centrifuge for centrifugation. The crystallized material enters the dryer for drying, and the centrifuge liquid returns to the single-effect evaporation system for further concentration. The material appears blue after drying. Samples are taken for testing, and the nickel content is 6% and the ammonium fluoride content is 90%. This is mainly because the main product obtained due to the high pH is ammonium fluoride, and the yield accounts for 68.3% of the total electrolytic waste residue (ammonium bifluoride absorbs part of the ammonia gas and converts it into ammonium fluoride). In addition, the nickel content is high and the appearance is poor, so the purification purpose cannot be achieved.

[0043] Comparative Example 3

[0044] In this comparative example, the mass proportion of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is 40%.

[0045] This comparative example is the same as Example 1, except that "adding solid potassium carbonate to adjust the pH to 10" is replaced by "adding solid potassium carbonate to adjust the pH to 8", and the specific steps are:

[0046] The recovery and purification process of ammonium bifluoride in the nitrogen trifluoride waste electrolyte is as follows: first, the nitrogen trifluoride waste residue is crushed to an average particle size of 1.0 cm, and then added to a dissolving kettle, water is added to dissolve according to a mass ratio of water to nitrogen trifluoride waste residue of 4:1, the temperature is controlled to be 65°C, ammonia is introduced to adjust the pH to 4.5, stirring is performed at a speed of 40 rpm, and stirring and reacting is continued for 3 hours after the introduction is completed, and then the mixture is pressed into a filter press by a delivery pump for filtration, and the primary filter mud is a nickel-containing material, and nickel is continued to be recovered; the primary filtrate after filtration is pumped into a decontamination tank, potassium carbonate solid is added to adjust the pH to 8, and stirring is performed at a speed of 40 rpm. After the addition is completed, stirring and reacting is continued for 4 hours, and then the mixture is pressed into a filter press by a delivery pump for filtration. After filtration separation, the secondary filter mud is a mixture of potassium fluoride silicate and nickel hydroxide, and nickel is further recovered. The secondary filtrate after filtration is light blue and stored in the filtrate tank. It is then pumped into the single-effect evaporation system by a delivery pump for single-effect concentration. When the mass concentration reaches 25%, the material is placed in a crystallization kettle and cooled to 2°C for crystallization. After 5 hours of reaction, the material is placed in a centrifuge for centrifugation. After centrifugation, the crystallized material enters the dryer for drying, and the centrifuge liquid returns to the single-effect evaporation system for further concentration. After drying, the material is sampled and tested. According to GB / T28655-2012, its content is 93.1%. The nickel content is 2% and other impurity components are 4.9% by atomic absorption. Qualified ammonium bifluoride cannot be obtained, and its yield is calculated to be 96.5%.

Claims

1. A process for recovering and purifying ammonium bifluoride from nitrogen trifluoride waste electrolyte, characterized in that: The nitrogen trifluoride waste residue is crushed to an average particle size of 0.8-1.2 cm, dissolved in water according to a mass ratio of water to nitrogen trifluoride waste residue of 4:1-5:1, the temperature is controlled at 60°C-70°C, ammonia is introduced to adjust the pH to 4.5-5, stirring is carried out at a speed of 40 rpm-50 rpm, and stirring is continued for 2h-3h after the introduction is completed, and the filtrate is taken after pressure filtration, potassium carbonate solid or potassium carbonate solution with a mass concentration of 10%-40% is added to adjust the pH to 9-10, stirring is carried out at a speed of 40 rpm-50 rpm, and stirring is continued for 3h-4h after the addition is completed, and the filter mud after pressure filtration is recovered. Nickel is concentrated by single effect, and when the mass concentration of ammonium bifluoride reaches 25%, pressure filtration is carried out, and the filtrate after pressure filtration is crystallized at 0-5°C for 4-6h, centrifuged, and dried to obtain pure ammonium bifluoride; The mass proportion of ammonium bifluoride in the nitrogen trifluoride waste residue is 40%-45%, the mass proportion of nickel element is 2.5%-3.5%, the mass proportion of nickel fluoride ammonia complex is 28%-32%, the mass proportion of copper fluoride ammonia complex is 2%-3%, the mass proportion of iron fluoride is 8%-10%, the mass proportion of water is 2%-3%, and the balance is fluorosilicate.