Study On Roasted Ceramsites Mixed With Electroplating Sludge

Electroplating sludge refers to the sludge produced by manufacturing industry after concentrated disposal to the metal surface waste liquid. Since it contains various heavy metal ions in different types and concentrations such as Nickel, Chromium, Zinc, Lead and Copper, casual abandonment will bring about great hazard to the soil and threaten the animals, plants and human health. Therefore, China has listed electroplating sludge into the Hazardous Waste List and implemented strict supervision and management as a kind of hazardous waste. With the constant transfer of manufacturing industries from developed countries into our country, China has had an increasing production volume of electroplating sludge which has thus become one of the major hazardous waste sources. According to an incomplete statistics, more than 20,000t electroplating sludge will be produced in Shanghai each year. And most irrecoverable electroplating sludge must be disposed safely. Even though a small amount of electroplating sludge featured as high concentration and single source has been recovered with heavy metal ion, the residue shall be disposed safely as the electroplating sludge. The expense of safety disposal is considerable. As a substitute method of temporary safety disposal, the electroplating sludge shall be mixed into clay for brick fabrication. Although this method is still contraversial to standard accordance of toxicity extraction index, it has settled the urgent orientation of electroplating sludge within a short period of time. With the adjustment of national policies, limited land resources are protected by law. It has been prohibited to calcinate clay bricks in some developed areas in China such as Shanghai. According to the current actual conditions in various areas of the country, safety disposal facilities of hazardous waste are far from complete. Most of the provinces, cities and regions have not established disposal hardware facilities in accordance with the safety disposal requirements of hazardous waste. In spite of disposal ability to the electroplating sludge, the safety disposal price of 2000 Yuan/ton will stop most of the enterprises. The orientation of electroplating sludge has become the urgent problem requiring for immediate solution.At the same time, coal fly ash utilized as construction material for a long time in Shanghai has become abundant under the influence of construction scale, circulation and financial crisis; but the sewage water biochemical disposal technologies in Shidongkou, Zhuyuan and Bailonggang sewage water disposal plants have produced huge amount of active sludge which requires for proper disposal orientation. Therefore, this research has a great realistic significance.Based on the above facts, this research has followed the guidance of energy-saving, discharge reduction and circulation economic principle, searched for the starting point of utilization direction mainly using electroplating sludge and including other solid waste such as coai fly ash and active sludge and changed "waste" requiring for paid disposal into product raw materials that can bring economic benefits. On the basis of initial research to the basic features of electroplating sludge, coal fly ash, active sludge and ceramisite fabrication, the feasibility of grinding and mixing above three raw materials as the raw material of ceramisite calcination shall be analyzed. The experimental research shall be conducted with ceramisite cylinder pressure as the main index to first find out the most suitable mixing ratio of ceramisite calcination with three raw materials. The orthogonal test shall be conducted on such a basis to find out the optimal pre-heat temperature and time of ceramisite calcination, optimal calcination temperature and time and analyze the cylinder pressure strength, surface density and water absorption rate. Then Guangxi white mud shall be utilized to test the index influence of different calcination environmental conditions on the ceramisite calcination under the best raw materials adding proportion. Finally, two calcination ceramisite shall be introduced into the production practice. Several frequently utilized and different production technical conditions shall be compared to select the production technique suitable to the researched and fabricated ceramisite. Besides, economic benefit analysis shall be conducted to the production of coal fly ash ceramisite, electroplating sludge coal fly ash ceramisite and the electroplating sludge coal fly ash ceramisite added with Guangxi white mud with the view to gain initial conclusion and suggestions.Generally speaking, this thesis has mainly researched into the following content: first, identify whether toxicity extraction of ceramisite calcinated by electroplating sludge or electroplating sludge accords with relevant requirements of Identification standards for hazardous wastes-Identification for extraction toxicity (GB5085.3-2007). This is the critical issue in deciding the re-utilization of electroplating sludge. Secondly, identify the possibility of ceramisite fabrication by mixing electroplating sludge into the raw materials. Since very few existent experiences can be borrowed during the attempt, there is both chance of success and failure. Thirdly, the influence of calcination environmental changes on ceramisite shall be investigated. The influence of changes in different raw materials adding proportion, different pre-calcination temperature and time, different calcination temperature and time on the ceramisite calcination parameters shall be analyzed to reasonably take or eliminate calcination conditions. Fourthly, the orthogonal test shall be conducted to optimize the ceramisite alcination conditions. Given numerous elements affecting the ceramisite calcination such as raw materials adding proportion, pre-calcination temperature and time and calcination temperature and time, the orthogonal test shall be conducted to complete the task. Fifthly, a contrast analysis shall be conducted to the test results using different additives. Under the condition of basically unchanged electroplating sludge and coal fly ash materials, Guangxi white mud shall be added as the additive for ceramisite calcination. The influence of different additives on ceramisite performance can be obtained through this contrast analysis. Sixthly, production technical selection and economic benefit analysis shall be conducted. Research shall be made into concrete techniques in introducing ceramisite fabrication (adding electroplating sludge) into the real production and concrete economic benefits to enable research to better serve the production practice.This thesis refers to the applicability research into ceramisite calcination by adopting raw materials such as electroplating sludge, coal fly ash and so on. Numerous research methods have been adopted in the concrete research. Investigation and visit researches are the main form at the initial period while experimental research has been made adopted in the late period. The content analytical method has been adopted in the basic research of ceramisite calcination raw materials to seriously analyze the features of various collected raw materials and ceramisite product to have certain knowledge. In the late period experimental research, observation research method has been adopted to analyze and research the appearance features of ceramisite calcination; and individual research method has been adopted to analyze the calcinated ceramisite under different mixing ratio and environmental conditions. Besides, relevant research methods have been integrated to make a contrast with the calcinated haydie under other mixing ratio and environmental conditions. Later, a quantitative analysis has been conducted to the cylinder pressure strength, water absorption rate and surface density of calcinated ceramisite by integrating qualitative research to obtain the best raw materials proportion and calcination environmental conditions. Finally, comparative analytical method has been adopted to make a quantitative comparison to the economic benefits in ceramisite production with different production techniques and raw materials.We can mainly come to the following conclusion through research in this dissertation:1. It is able to calcinate ceramisite by mixing electroplating sludge and active sludge into the coal fly ash. There are numerous raw materials for ceramisite calcination. And the decisive factor lies in the content ratio of silicon dioxide and aluminium oxide in the raw material. Once the content of above two substances has reached above 80%, the initial conditions for ceramisite calcination have been prepared. Research has shown that the content of above two substances in normal coal fly ash is higher than this ratio. The electroplating sludge and active sludge contain these two substances. At the same time, they contain other metal ions. After a certain ratio of electroplating sludge and active sludge has been added into the coal fly ash, the ceramisite calcination content of silicon dioxide and aluminium oxide can be maintained and heavy metal ion can play a catalytic role——it can not only enhance the ceramisite strength, but also accelerate the calcination speed. The later tests have proven the theoretical judgement.2. Different raw materials mixing ratio will have a rather great influence on the strength of ceramisite calcination. During the test, three groups (X, Y, Z) of samples in different raw materials mixing ratio have been prepard in order to test the influential degree of different raw materials mixing ratio on the ceramisite calcination index. Each group contains 4 samples. The coal fly ash adding ratio changes between 55%-85%; the electroplating sludge adding ratio changes between 0%-40%; the active sludge adding ratio changes between 5%-15%. The result has shown that ceramisite has great color difference under calcination in different raw materials mixing ratio; ceramisite strength gap is 15.5 times. The mixing ratio leading to maximum ceramisite strength is as follows: electroplating sludge: coal fly ash: active sludge= 10:80:5.3. The orthogonal test shall be conducted to find out the optimal environmental conditions for ceramisite calcination. Test has proven that apart from great influence of raw materials ingredient on ceramisite strength, different pre-heat temperature and time and calcination temperature and time will also have rather great influence on ceramisite calcination. The orthogonal test shall be introduced for sieving process in order to find out the optimal calcination conditions. No. 10 sample in the orthogonal test has the greatest ceramisite strength. The cylinder pressure strength is 4.526MPa. And high quality product standard has been reached; the water content rate is 27.3%. Once the index of four elements has reached 700℃pre-heat temperature, 15min pre-heat time, 1200℃calcination temperature and 30min calcination time, ceramisite with maximum cylinder pressure strength can be calcinated.4. After Guangxi white mud is added into the raw material, the ceramisite has obvious change index and cylinder pressure strength is greatly enhanced. The objective of adding Guangxi white mud is to observe ceramisite index changes and compare with electroplating sludge ceramisite without Guangxi white mud. Efforts shall be made to enrich the prescription and choice of electroplating sludge ceramisite calcination. The test is divided into two groups and each group has 32 tests. The additing ratio of Guangxi white mud shall remain 20%. The adding ratio of electroplating sludge has a change margin of 20%-35%, active sludge is 10%-15% and coal fly ash is 30%-50%. The result has shown that the water absorption rate gap of ceramisite is as high as 6993.5 times; the surface density changes between 745.5 kg/m~3-1671.7 kg/m~3. Compared with electroplating sludge ceramisite without Guangxi white mud, the cylinder pressure strength of ceramisite has been generally enhanced. 10.35Mpa ceramisite level has been obtained in the samples. The optimal prescription ratio and calcination environmental conditions in adding Guangxi white mud are as follows: electroplating sludge content: 30%; coal fly ash content: 40%; active sludge content: 10%; Guangxi white mud content: 20%; pre-heat temperature: 600℃; pre-heat time: 15 minutes; calcination temperature: 1175℃; calcination time: 25 minutes.5. The production technique in electroplating sludge ceramisite fabrication shall be selected and economic benefit analysis shall be conducted. The sintering techniques shall be selected for the sinterer through comparison. The net profit in 1m~3 product production is as follows: 20.5 Yuan for coal fly ash ceramisite, 160.125 Yuan for electroplating sludge ceramisite and 503.125 Yuan for electroplating sludge ceramisite added with Guangxi white mud. It means that electroplating sludge ceramisite calcination enjoys obvious economic benefits.Research has shown that there is a broad prospect for electroplating sludge ceramisite production.