Technology of non-burned brick using MSW gasification slag and solidification of heavy metal课件

1、Title: Technology of non-burned brick using MSW gasification slag and solidification of heavy metalAuthors: Yiren WangChunping Li Aiqin Wang Feihua Yang Liwei Hao PAPER DEADLINE: PAPER LENGTH: SEND PAPER TO: Chunping Li Department of Cement and environment protection Beijing building materials acade

2、my of sciences research 100041 Beijing China Tel: +86 88752127Fax: +86 88752714E-mail: lichp-ABSTRACT Ten sets of experiments were designed to process non-burnt bricks by adding 10% of cement as binder and different proportion of carbide slag as activator into municipal solid waste (MSW) gasificatio

3、n and incineration slag. The results showed that: compressive strength at 3d, 7d and 28d of non-burnt bricks compound by T2 were the highest with 10.552MPa, 19.291 MPa and 20.135 MPa respectively, achieving the high quality standard brick. Besides, leaching concentration of heavy metals were lower t

4、han that of GB3838-2002 environmental quality standard for surface water in V water requirements; heavy metals Pb, Zn, Cu, Cd mostly exist in the organic and residual fraction with 99.97%, 82.93%, 89.55% and 74.20% of the total fraction, respectively.0 INTRODUCTION Incineration technology is conside

5、red to be one of the most effective means which can realize the harmless, reduction and recycling of municipal solid waste (MSW)1,2, but there is a secondary pollution problems of direct incineration waste, for example, low processing rate, high energy consumption and acid gases, dioxins, fly ash em

6、issions3,4.However, Gasification technology is called a new generation of waste treatment technologies as an alternatives to energy recovery and waste treatment and, has great potential foreground5,6. But, in China, gasification will produce part of the bottom slag due to more inorganic substance co

7、ntained in MSW. So, bottom slag reusing technology has also become the new research direction. The traditional sintered clay bricks destroy arable land, consume high energy and emit air pollutants in the process of production. In order to save energy, protect land resources and ecological environmen

8、t, China has strongly advocated to produce all kinds of non-sintered clay brick, blocks and plates and other regeneration wall materials using a variety of industrial solid waste as raw Yiren Wang1, Chunping Li2, Aiqin Wang1,2*, Feihua Yang2,Liwei Hao2（1. Zhongyuan University of Technology, Zhengzho

9、u Henan Province 450007，China; 2. Beijing Building Materirals Academy of Science Research/Solid Waste Resources Utilization and Energy Saving Building Materials State Key Laboratory, Beijing 100041, China)materials7,8. Many scholars had studied preparation of non-burnt brick made from coal gangue, w

10、aste incineration slag9, but the preparation of non-burnt bricks using gasification of bottom slag is relatively rare. In this study, refuse derived fuel (RDF) gasification bottom slag was studied as an object to explore the effect of different mixture ratio on the non-burnt brick strength and heavy

11、 metals solidification and, to provide the new technical for comprehensive utilization of waste.1 MATERIALS AND METHODS(1) Experimental method After gasification the RDF at 800 , air atmosphere and sampling incineration bottom ash of a incineration plant in Beijing as compare, non-burnt bricks were

12、pressed out using homemade model at 20MPa with the size of 200mm100mm50mm, and, compressive strength of non-burnt bricks was tested at 3d, 7d and 28d. Heavy metals characteristics of non-burnt bricks were measured by grinding the sample through 100 mesh sieve. (2) Measurement indicators and methods

13、Compressive strength was tested by using cement pressure testing machine at stressing speed of 2.4kN/s. Mineral composition was measured by XRD and activity was measured referencing GB/T12597-2005. Refer the relevant national standards(GB5085.3-2007,CJ/T221-2005) to measure the total amount of the h

14、eavy metals As、Cd、Hg、Cu、Pb、Cr、Zn in the leaching solution. Using an improve BCR method to measure the form of the heavy metals.2 RESULTS AND DISCUSSION2.1 Materials Characteristic Analysis Analysis of the characteristics of refuse derived fuel (RDF) gasification bottom slag (gasification slag) and B

15、eijings waste incineration bottom slag (incineration slag) were listed in Table 1.Table 1 Material characteristics of two slagsSample NameActivitySiAlFeCaOKNaSClgasification slagUnqualified23.4811.254.5211.261.973.032.681.79Incineration slagUnqualified54.3113.545.8721.251.541.691.220.58 As can be se

16、en from Table 1: as compared to incineration slag, the gasification combustion is not a complete incineration, therefore, contents of Ca, Si, Al, Fe in RDF gasification bottom slag is less than that in incineration bottom slag , RDF gasification bottom slag may be contain more other components, such

17、 as residual carbon, etc.10. Besides, fixed chlorine reagents had been added during RDF preparation11, sulfur content and chlorine content in gasification bottom slag was significantly higher than that in incineration bottom slag, indicated that fixed chlorine reagents have significant effects on fi

18、xed sulfur and chlorine elements. The activity of two kinds of bottom slag were both unqualified, cannot be directly used as non-burnt brick preparation, which need to add some gelling material and exciting agent12.2.2 Best proportion of raw materials(1) Match ratio of raw material According to 3R p

19、rinciples of waste and JC/T422-2007 non-sintered common brick MU15 standard, 10 set of experiments were designed by adding 10% of cement as a binder12 and different ratio of carbide slag as the activator, noted as T1, T2, T3, T4, T5, T6, T7, T8, T9, T10. The proportion of each raw material was shown

20、 in Table 2.Table 2 Raw materials proportioning of non-burnt bricksT1T2T3T4T5Carbide Slag510152025Cement1010101010Gasification slag8580757065T6T7T8T9T10Carbide Slag510152025Cement1010101010Incineration slag8580757065(2)Compressive strength of non-burnt brick of different proportion Compressive stren

21、gth of non-burnt bricks was tested by using cement pressure testing machine at stressing speed of 2.4kN/s at 3d, 7d and 28d. Measuring results shown in Figure 1.5791113151719213d7d28dtimeCompressive strength（MPa）T1T2T3T4T5T6T7T8T9T10Fig. 1 Compressive strength of non-burnt bricks As can be seen from

22、 Figure 1: between 10 sets of experiments, non-burnt brick compressive strength of T2 at 3d, 7d and 28d were the highest with the value of 10.552MPa, 19.291 MPa and 20.135 MPa respectively, followed by T3, the compressive strength at 3d, 7d and 28d were 7.313MPa, 15.578 MPa and 16.804 MPa respective

23、ly. T3 has reached eligibility in accordance with national JC/T422-2007 non-sintered common brick criteria, and T2 has reached high brick quality standards, other treatments have failed. Therefore, the appropriate proportion of non-burnt brick was T2, with the dosages of carbide slag, cement and gas

24、ification bottom slag were 10%, 10% and 80% respectively.2.3 Characteristics of heavy metals Heavy metals are major pollutants in waste with characteristics of difficult movement and easy enrichment and become a limiting factor in recycling of waste. Toxicity of heavy metals not only related to leac

25、hing, but to a greater extent which determined by the distribution of chemical speciation13. In the study on morphological distribution of heavy metals, improved BCR three-step extraction method has the merit of good stability and reproducibility, high extraction accuracy, comparable results of diff

26、erent studies, which has been widely used in sediment, soil, sludge and other different heavy metal form analysis of environmental samples by the EC bureau of standards14. In this study, take the non-burnt brick made by T2 as study object, leaching concentration and activity of heavy metals were mea

27、sured to assess the characteristics of heavy metals in non-burnt brick.(1)Total amount of heavy metals in the leachate Take part of brick made by T2 as sample, grind the sample through 100 mesh sieve and measure the total amount of heavy metals in the leaching. Measuring results was shown in Table 3

28、.Table 3 Leaching concentration of heavy metals from non-burnt brickZnCuPbCdCrAsHgT2186.5459.81.3910.8420.1651.6500.575 As can be seen from Table 3, leachate concentrations of heavy metals in non-burnt brick were lower than requirements of GB3838-2002 Surface Water Quality Standards Class V.(2)Heavy

29、 metal fraction Take part of brick made by T2 as sample, grind the sample through 100 mesh sieve and measure the fraction of Pb、Zn、Cu、Cd . Measuring results was shown in Figure 2.020406080100PbZnCuCdfraction（%）residual fractionoxidisable fractionreducible fractionexchangeable fractionFig. 2 Heavy me

30、tals fraction in non-burnt brick It was generally considered that exchangeable fraction of heavy metals are harmful to humans and the environment, while organic fraction of heavy metals are more stable and, residual fraction are generally called ineffective state because this fraction of the heavy m

31、etals is difficult to release in natural conditions15. As can be seen from Figure 2, heavy metals of Pb, Zn, Cu, Cd are mostly bounded to organic fraction and residual fraction in non-burnt brick made by T2 , with amounts of 99.97%、82.93%、89.55% and 74.20% respectively, which means that the heavy me

32、tals are relatively stable and not easily leached out with rainfall or transfer to the surrounding environment.3 CONCLUSION (1) Contents of Ca, Si, Al, Fe in RDF gasification bottom slag is less than that in incineration bottom slag and sulfur content and chlorine content in gasification bottom slag

33、 was significantly higher than that in incineration bottom slag. The activity of two kinds of bottom slag were both unqualified, cannot be directly used as non-burnt brick preparation and need to add some gelling material and exciting agent. (2) Between 10 sets of experiments, non-burnt brick compre

34、ssive strength of T2 at 3d, 7d and 28d were the highest with the value of 10.552MPa, 19.291 MPa and 20.135 MPa respectively, followed by T3, the compressive strength at 3d, 7d and 28d were 7.313MPa, 15.578 MPa and 16.804 MPa respectively. Therefore, the appropriate proportion of non-burnt brick was

35、T2, with the dosages of carbide slag, cement and gasification bottom slag were 10%, 10% and 80% respectively. (3) Leachate concentrations of heavy metals in non-burnt brick were lower than requirements of GB3838-2002 Surface Water Quality Standards Class V. Heavy metals of Pb, Zn, Cu, Cd are mostly

36、bounded to organic fraction and residual fraction in non-burnt brick made by T2, with amounts of 99.97%、82.93%、89.55% and 74.20% respectively, which means that the heavy metals are relatively stable and not easily leached out with rainfall or transfer to the surrounding environment.ACKNOWLEDGEMENTST

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