水玻璃旧砂干法再生研究
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摘要
就旧砂再生而言，水玻璃旧砂再生相对最为困难，废弃的旧砂为碱性，所倾倒之处寸草不生，加上我国优质石英砂资源相对短缺，如果不对水玻璃旧砂综合利用而大量废弃，就是对有限资源的极大浪费，而且造成严重的环境污染。因此，水玻璃旧砂的处理和利用已成为铸造行业通过清洁生产向绿色铸造转变需亟待解决的问题。
本文针对水玻璃旧砂的性质进行了较全面的分析和研究，结合硬化膜与惰性膜的关系开展了水玻璃惰性薄膜与再生方式的相关关系的研究，然后结合旧砂再生机理有针对性的选择合适的再生方法对水玻璃旧砂进行相对不同的再生处理，对再生砂从铸造常规性能、粒貌进行评价，根据铸钢用水玻璃型(芯)砂的生产要求，对再生砂开展优化工艺实验，考量再生砂满足生产要求的程度及可行性，验证再生工艺的再生效果，其最终目的是使再生砂能全部或者部分取代新砂造型、制芯，减少旧砂排放。
对水玻璃旧砂表面膜及其性质的研究表明：1)水玻璃砂吹CO_2硬化后的硬化膜由晶体和非晶体共同组成，主要由非晶态硅酸凝胶和少量的柯石英晶体(单斜晶系)、Na_2CO_3·7H_2O晶体组成；硬化膜在受热作用转化为惰性膜后，主要由非晶态硅酸凝胶和少量的SiO_2晶体(六方晶系)、Na_2SiO_3·9H_2O晶体(正交晶系)组成，可为再生方法选择提供参考依据；2)水玻璃砂烘干硬化后的硬化膜是晶体和非晶体共同组成的硬化膜，主要由Na_2SiO_3非晶体和少量的Na_2SiO_3晶体组成；硅酸盐硬化膜在受热作用后转化为硅酸盐惰性膜。
对水玻璃旧砂进行三种相对不同再生处理的实验表明，搅拌加热—冲击—摩擦磨损再生实验与微波加热—冲击—摩擦磨损再生实验就再生砂氧化钠含量而言，都可降低旧砂的氧化钠含量，通过搅拌加热—冲击—摩擦磨损再生，使旧砂氧化钠含量降低70.11％，微波加热—冲击—摩擦磨损再生可使旧砂氧化钠含量降低53.6％，加热方式的不同对两者再生效果有一定的影响，由于前者加热时连续不断的搅拌使旧砂砂粒相互摩擦，在一定程度上起到了初级再生的作用，因此再生效果前者优于后者。通过正交实验表明，旧砂的加热温度是对再生效果影响较大，进一步说明了水玻璃旧砂砂粒中的石英颗粒随加热温度升高导致的膨胀与水玻璃惰性膜脆性提高、收缩的共同作用下，可提高再生效果。
摩擦磨损再生可使旧砂氧化钠含量降低61.77％，因此法已达到中试生产阶段，无需加热处理，属短流程再生工艺，故旧砂再生生产线摩擦磨损再生工艺有较大的现实意义，即具有较好的可行性。
考虑到通过加热方法对水玻璃就旧砂进行再生需耗能的缘故，采用摩擦磨损再生方法对水玻璃旧砂进行再生，该再生砂用于水玻璃粘结剂型(芯)砂的工艺实验的配方优化实验表明，在再生砂加入量为100％、水玻璃加入量为5％和二氧化碳吹气时间为10s的工艺条件下，型砂的抗压强度大于0.9Mpa，可达到生产的要求。
Speaking of the old granulated substance regeneration, sodium silicate old granulated substance regeneration is relative most difficult, abandons old granulated substance for alkalinity, falls place grass all long, adds on our country high quality quartz sand resources relatively short, if does not add water the glass old granulated substance comprehensive utilization to abandon massively, is to the limited resources enormous waste, moreover creates serious environmental pollution. Therefore, sodium silicate old granulated substance processing and the use have become question which the entire society urgently awaits to be solved.
This article has carried on the comprehensive analysis and the research in view of the sodium silicate old granulated substance nature, the union stuck the conjunctiva, the hardened membrane, the inert membrane relations has developed the exploration sodium silicate inert thin film and the regeneration way correlational dependence research, then unifies the old granulated substance regeneration mechanism to have the pointed choice appropriate regeneration method adding sodium silicate bonded old granulated substance to carry on relatively different regeneration processing, to green sand for castings from the casting convention performance, a grain of appearance carries on the appraisal again, according to cast used steel sodium silicate bonded sand (core) granulated substance production request, to green sand for castings the development optimization craft experiment, the consideration again green sand for castings satisfies the production request again the degree and the feasibility, the confirmation regeneration craft regeneration effect, its final goal is enables again green sand for castings completely or the part substitution new sand modelling, the system core, reduces the old granulated substance emissions.
The used sodium silicate bonded sand surface film and the nature research indicates : 1) The used sodium silicate bonded sand after hardened membranes are the hardened membrane which the crystal and the amorphous body compose together, mainly by amorphous state acid gelatin and few tan oak quartz crystal、Na_2CO_3·7H_2O crystal compositions; The acid gelatin hardening membrane transforms in the being heated function after the inert membrane, mainly for the acid gelatin inert membrane and the few crystal, the crystal of Na_2SiO_3·9H_2O (rhombic system), has provided the reference for the choice regeneration method;2) Sodium silicate granulated substance drying hardens the after hard membrane is the hardened membrane which the crystal and the composes together, mainly is composed by the amorphous body and the few crystals; The silicate hardening membrane transforms after the being heated function as the silicate inert membrane.
The adding used sodium silicate bonded sand granulated substance sand grain surface inert thin film and the nature research indicated, The sodium silicate (core) the granulated substance different hardening craft and the sodium silicate inert membrane has certain relation, unifies the old granulated substance regeneration mechanism according to the inert membrane nature to have the pointed choice appropriate regeneration method to carry on regeneration processing to the old granulated substance.
The adding used sodium silicate bonded sand granulated substance carries on relatively different regeneration processing the experiment to indicate, the mechanical agitation heating - impact - friction attrition regeneration experiment and the microwave heating - impact - friction attrition regeneration experiment speaking of again green sand for castings the sodium oxide content, all may reduce the old granulated substance the sodium oxide content, among them, old granulated substance sodium oxide content 0 .446%, the mechanical agitation heating - impact - friction wears green sand for castings the sodium oxide content to be again lowest may be 0.1333%, the microwave heating - impact - friction wears green sand for castings the sodium oxide content to be again lowest may be 0.207%. The heating way to both regeneration effect influence difference is not differently very big, but because time the former heating the continuously agitation causes the old granulated substance sand grains to rub mutually, played to a certain extent the primary regeneration role, therefore regeneration effect the former surpasses the latter. Indicated through the orthogonal experiment, the old granulated substance heating temperature is to regenerates the effect influence to be big, further explained in the sodium silicate old granulated substance sand grains quartz grain the inflation and sodium silicate inert membrane brittleness which causes along with the heating temperature ascension enhances, under the contraction together function, may enhance the regeneration effect.
Considered carries on the reason through the heating method adding sodium silicate bonded on the old granulated substance which the regeneration must consume energy, uses the friction attrition regeneration method adding used sodium silicate bonded granulated substance to carry on the regeneration, this green sand for castings uses in the sodium silicate caking dosage-form (core) the granulated substance craft experiment formula optimization experiment indicating again, in green sand for castings joins the quantity is again 100%, the sodium silicate joins the quantity is 5% and the carbon dioxide air flush time under 10s technological conditions, molding sand compressive strength big 0.9Mpa, may achieve the production the request.
本文针对水玻璃旧砂的性质进行了较全面的分析和研究，结合硬化膜与惰性膜的关系开展了水玻璃惰性薄膜与再生方式的相关关系的研究，然后结合旧砂再生机理有针对性的选择合适的再生方法对水玻璃旧砂进行相对不同的再生处理，对再生砂从铸造常规性能、粒貌进行评价，根据铸钢用水玻璃型(芯)砂的生产要求，对再生砂开展优化工艺实验，考量再生砂满足生产要求的程度及可行性，验证再生工艺的再生效果，其最终目的是使再生砂能全部或者部分取代新砂造型、制芯，减少旧砂排放。
对水玻璃旧砂表面膜及其性质的研究表明：1)水玻璃砂吹CO_2硬化后的硬化膜由晶体和非晶体共同组成，主要由非晶态硅酸凝胶和少量的柯石英晶体(单斜晶系)、Na_2CO_3·7H_2O晶体组成；硬化膜在受热作用转化为惰性膜后，主要由非晶态硅酸凝胶和少量的SiO_2晶体(六方晶系)、Na_2SiO_3·9H_2O晶体(正交晶系)组成，可为再生方法选择提供参考依据；2)水玻璃砂烘干硬化后的硬化膜是晶体和非晶体共同组成的硬化膜，主要由Na_2SiO_3非晶体和少量的Na_2SiO_3晶体组成；硅酸盐硬化膜在受热作用后转化为硅酸盐惰性膜。
对水玻璃旧砂进行三种相对不同再生处理的实验表明，搅拌加热—冲击—摩擦磨损再生实验与微波加热—冲击—摩擦磨损再生实验就再生砂氧化钠含量而言，都可降低旧砂的氧化钠含量，通过搅拌加热—冲击—摩擦磨损再生，使旧砂氧化钠含量降低70.11％，微波加热—冲击—摩擦磨损再生可使旧砂氧化钠含量降低53.6％，加热方式的不同对两者再生效果有一定的影响，由于前者加热时连续不断的搅拌使旧砂砂粒相互摩擦，在一定程度上起到了初级再生的作用，因此再生效果前者优于后者。通过正交实验表明，旧砂的加热温度是对再生效果影响较大，进一步说明了水玻璃旧砂砂粒中的石英颗粒随加热温度升高导致的膨胀与水玻璃惰性膜脆性提高、收缩的共同作用下，可提高再生效果。
摩擦磨损再生可使旧砂氧化钠含量降低61.77％，因此法已达到中试生产阶段，无需加热处理，属短流程再生工艺，故旧砂再生生产线摩擦磨损再生工艺有较大的现实意义，即具有较好的可行性。
考虑到通过加热方法对水玻璃就旧砂进行再生需耗能的缘故，采用摩擦磨损再生方法对水玻璃旧砂进行再生，该再生砂用于水玻璃粘结剂型(芯)砂的工艺实验的配方优化实验表明，在再生砂加入量为100％、水玻璃加入量为5％和二氧化碳吹气时间为10s的工艺条件下，型砂的抗压强度大于0.9Mpa，可达到生产的要求。
Speaking of the old granulated substance regeneration, sodium silicate old granulated substance regeneration is relative most difficult, abandons old granulated substance for alkalinity, falls place grass all long, adds on our country high quality quartz sand resources relatively short, if does not add water the glass old granulated substance comprehensive utilization to abandon massively, is to the limited resources enormous waste, moreover creates serious environmental pollution. Therefore, sodium silicate old granulated substance processing and the use have become question which the entire society urgently awaits to be solved.
This article has carried on the comprehensive analysis and the research in view of the sodium silicate old granulated substance nature, the union stuck the conjunctiva, the hardened membrane, the inert membrane relations has developed the exploration sodium silicate inert thin film and the regeneration way correlational dependence research, then unifies the old granulated substance regeneration mechanism to have the pointed choice appropriate regeneration method adding sodium silicate bonded old granulated substance to carry on relatively different regeneration processing, to green sand for castings from the casting convention performance, a grain of appearance carries on the appraisal again, according to cast used steel sodium silicate bonded sand (core) granulated substance production request, to green sand for castings the development optimization craft experiment, the consideration again green sand for castings satisfies the production request again the degree and the feasibility, the confirmation regeneration craft regeneration effect, its final goal is enables again green sand for castings completely or the part substitution new sand modelling, the system core, reduces the old granulated substance emissions.
The used sodium silicate bonded sand surface film and the nature research indicates : 1) The used sodium silicate bonded sand after hardened membranes are the hardened membrane which the crystal and the amorphous body compose together, mainly by amorphous state acid gelatin and few tan oak quartz crystal、Na_2CO_3·7H_2O crystal compositions; The acid gelatin hardening membrane transforms in the being heated function after the inert membrane, mainly for the acid gelatin inert membrane and the few crystal, the crystal of Na_2SiO_3·9H_2O (rhombic system), has provided the reference for the choice regeneration method;2) Sodium silicate granulated substance drying hardens the after hard membrane is the hardened membrane which the crystal and the composes together, mainly is composed by the amorphous body and the few crystals; The silicate hardening membrane transforms after the being heated function as the silicate inert membrane.
The adding used sodium silicate bonded sand granulated substance sand grain surface inert thin film and the nature research indicated, The sodium silicate (core) the granulated substance different hardening craft and the sodium silicate inert membrane has certain relation, unifies the old granulated substance regeneration mechanism according to the inert membrane nature to have the pointed choice appropriate regeneration method to carry on regeneration processing to the old granulated substance.
The adding used sodium silicate bonded sand granulated substance carries on relatively different regeneration processing the experiment to indicate, the mechanical agitation heating - impact - friction attrition regeneration experiment and the microwave heating - impact - friction attrition regeneration experiment speaking of again green sand for castings the sodium oxide content, all may reduce the old granulated substance the sodium oxide content, among them, old granulated substance sodium oxide content 0 .446%, the mechanical agitation heating - impact - friction wears green sand for castings the sodium oxide content to be again lowest may be 0.1333%, the microwave heating - impact - friction wears green sand for castings the sodium oxide content to be again lowest may be 0.207%. The heating way to both regeneration effect influence difference is not differently very big, but because time the former heating the continuously agitation causes the old granulated substance sand grains to rub mutually, played to a certain extent the primary regeneration role, therefore regeneration effect the former surpasses the latter. Indicated through the orthogonal experiment, the old granulated substance heating temperature is to regenerates the effect influence to be big, further explained in the sodium silicate old granulated substance sand grains quartz grain the inflation and sodium silicate inert membrane brittleness which causes along with the heating temperature ascension enhances, under the contraction together function, may enhance the regeneration effect.
Considered carries on the reason through the heating method adding sodium silicate bonded on the old granulated substance which the regeneration must consume energy, uses the friction attrition regeneration method adding used sodium silicate bonded granulated substance to carry on the regeneration, this green sand for castings uses in the sodium silicate caking dosage-form (core) the granulated substance craft experiment formula optimization experiment indicating again, in green sand for castings joins the quantity is again 100%, the sodium silicate joins the quantity is 5% and the carbon dioxide air flush time under 10s technological conditions, molding sand compressive strength big 0.9Mpa, may achieve the production the request.
引文
[1]郭景纯，郭思福．铸造旧砂再生利用及污染治理．广州：中山大学出版社，2001
[2]胡彭生．型砂．上海：上海科学技术出版社，1994
[3]郭景纯．旧砂的再生和综合利用．铸造设备研究所，1997(1)：52～54
[4]FAS Trans.1992 vol20: 563
[5]CE Wenninger."Development of Foundry Sand Reclamation"AFS Trans,1953:191
[6]徐顺庆．国内外铸造机械概况和发展趋势．济南铸锻机械研究所，1979，9
[7]A Status Report of AFS Sand Recalamation & Reuse Committee (80-S). "Sand Reclamation".Modern Casting,1979(3):60
[8]First Report of Working Group P7. "Sand Reclamation".British Foundryman, 1973(8):45
[9]U Kleinheyer. "Sandaut Bereitung Sanlagen-Mschinen und-Zubekor auf der GIFA".Giesserei, 1962(21):710
[10]M Gras. "NaBputzunlogen unter Besonderer Beerucksichfigung des Entkernens Von SlahlguB".Giesserei,1963(11):337
[11]Weiss R，Kleinheryer U．目前旧砂再生和废砂处理的发展趋势．(德)中文版，铸造设备与技术，1989(15)
[12]今泉富士夫．日本旧砂再生的现状和未来．铸锻造与热处理．1978(12)：76
[13]ECJeter "Sand Reclamation for Ferrous Foundry".Foundry,1946(8):86
[14]CIATF Report of Commission 1.4. "Reclamation of Foundry Sand form Moldinggand Core Making Process".British
[15]用水力分级分选原砂和再生旧砂．铸工，1958(1)：23
[16]济南铸锻机械研究所．国内外水力清砂湿法再生装置概述及对某些问题的探讨。济南铸锻机械研究所，1963
[17]上海气轮机厂．水力旋游器-水力分级旧砂再生装置．铸锻机械，1976(3)：17
[18]重庆钢铁设计院通风科．风力送砂、湿法再生，调查报告之一，之二．重庆钢铁设计院，1973
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[33]石光玉．水玻璃干法再生工艺及其成套设备的研究．1990年全国铸造设备年会论文集
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[44]G Good et al. "Total Sand Reclamation".AFS Special Report, 1987(7): 154
[45]刘仲礼．铸造旧砂再生工艺及应用的研究．[研究生论文]昆明：昆明理工大学，2003：30
[2]胡彭生．型砂．上海：上海科学技术出版社，1994
[3]郭景纯．旧砂的再生和综合利用．铸造设备研究所，1997(1)：52～54
[4]FAS Trans.1992 vol20: 563
[5]CE Wenninger."Development of Foundry Sand Reclamation"AFS Trans,1953:191
[6]徐顺庆．国内外铸造机械概况和发展趋势．济南铸锻机械研究所，1979，9
[7]A Status Report of AFS Sand Recalamation & Reuse Committee (80-S). "Sand Reclamation".Modern Casting,1979(3):60
[8]First Report of Working Group P7. "Sand Reclamation".British Foundryman, 1973(8):45
[9]U Kleinheyer. "Sandaut Bereitung Sanlagen-Mschinen und-Zubekor auf der GIFA".Giesserei, 1962(21):710
[10]M Gras. "NaBputzunlogen unter Besonderer Beerucksichfigung des Entkernens Von SlahlguB".Giesserei,1963(11):337
[11]Weiss R，Kleinheryer U．目前旧砂再生和废砂处理的发展趋势．(德)中文版，铸造设备与技术，1989(15)
[12]今泉富士夫．日本旧砂再生的现状和未来．铸锻造与热处理．1978(12)：76
[13]ECJeter "Sand Reclamation for Ferrous Foundry".Foundry,1946(8):86
[14]CIATF Report of Commission 1.4. "Reclamation of Foundry Sand form Moldinggand Core Making Process".British
[15]用水力分级分选原砂和再生旧砂．铸工，1958(1)：23
[16]济南铸锻机械研究所．国内外水力清砂湿法再生装置概述及对某些问题的探讨。济南铸锻机械研究所，1963
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