The technology of coal gangue and fly ash waste wall material products bricks
4. Issues to be paid attention to in promoting the technology of coal gangue and fly ash waste wall material products
The research and application of coal gangue and fly ash in the wall material industry were introduced earlier. It should be said that there are many achievements and innovative points, but the actual application lags behind. Some research projects have achieved good results in market applications, but some projects often end up with results that have been neglected for many years. The main reasons for this phenomenon are: firstly, the depth of project research is not enough, and further improvement is needed in technology before promotion and application; Secondly, the unstable market and low recognition of products cause psychological barriers and reluctance to accept new things; Thirdly, when using coal gangue and fly ash projects, the investment in the same product is often greater than in traditional process projects, and there is a concern that the benefits will be affected. In addition, the policy of encouraging the use of bulk solid waste is not fully implemented. At the beginning of the project, the government attached great importance and provided small subsidies or free use of waste residue. When comprehensive utilization is transformed into raw materials and materials, although there is no clear charge, disguised charges have been adopted, such as helping to load vehicles, transportation, and other methods to increase prices and fees, resulting in difficulties in business operations and difficulty in survival. Some environmental protection departments do not see the trend of enterprises using coal gangue and fly ash industrial waste to protect the environment, but instead seize a certain emission defect of the enterprise and restrict its normal production. We will only see small issues that affect environmental protection in the production of enterprises, but not the big problem of pollution accumulation without waste residue. So, for innovative research on new wall material projects, it is necessary to increase support for their promotion and application, improve project technical conditions and promote application standards and specifications, and ensure that comprehensive utilization policies are not compromised. Otherwise, the research project will remain in the original small experiments and theoretical research results for a long time.
What kind of wall material products should be developed for coal gangue and fly ash? I personally believe that careful analysis and research should be conducted before making a decision. Firstly, the following three experimental analysis tasks should be done well. One is to conduct heat generation tests on coal gangue, fly ash, or slag ash to determine whether to develop sintered wall material products or non sintered products. High calorific value coal gangue and fly ash are not suitable for developing non sintered products. Sintered products should be chosen first, and the production process does not use coal or uses less coal. Low calorific value or relatively non calorific value, can be used for non sintered products. High heat coal gangue and fly ash are directly used in non sintered wall materials. Due to the presence of carbon, not only is heat wasted, but also the strength, frost resistance, and durability of the products are greatly affected. The second is chemical composition testing, with special attention paid to the content of silicon dioxide (SiO ₂), aluminum trioxide (Al2O Å), iron trioxide (Fe2O Å), calcium oxide (CaO), and sulfur trioxide SO Å. Excessive or low silica content will ultimately affect product quality; High content of iron oxide can be considered for adjusting product color, and less than 1% can be used as a production ingredient for ceramic wall and floor tiles; Excessive calcium oxide content can easily cause lime cracking in sintered wall materials, which poses a safety hazard of wall cracking and cracking in buildings. Therefore, it is necessary to adjust the technical parameters of coal gangue and fly ash raw material treatment and firing process. However, it is beneficial to produce non sintered aerated concrete wall materials with a relatively high content of calcium oxide; If the sulfur oxide is too high, it will increase the emission of atmospheric pollutants such as sulfur gas from sintered products, increase the consumption of desulfurization materials, and significantly increase the production costs of enterprises. The third is the plasticity index. If it is too low, it cannot be extruded. If it is too high, it will increase drying shrinkage and the product is prone to stress cracks. Fly ash has no plasticity, but its functional properties can be improved through physical, chemical, and biological modifications, which is particularly important for non sintered products. The development of which product is based on raw materials, and product quality cannot be abandoned for the purpose of solid waste utilization. It is also important not to pursue unrealistic high quality and added value, which can affect the process and efficiency of utilizing large amounts of solid waste coal gangue and fly ash.