Papers by Keyword: Carbide Slag

Abstract: With development of the economic, China has been the largest cement production country in the world. But the big production of cement also causes serious ecological environmental problems. In this study, a cradle-to-gate life cycle assessment was carried out for four typical cement factories in China. The results indicated that new suspension preheater (NSP) process and power plant were mainly to blame for most emissions and environmental performances, and GWP is the most prominent category in the accumulative environmental performance of cement production. Any of the strategies for cleaner production of cement considered in this study, including larger production scale, cogeneration and using calcium carbide slag as secondary material, has effect in improving the environmental performance, but the final single result show that the utilization of calcium carbide slag is the best method, and it could reduce the environmental impact obviously.

Abstract: NaOH, Na2CO3 and NaNO3 loaded on carbide slag are used as transesterification catalysts in a batch-type transesterification system. The activated catalysts are characterized by X-ray diffraction and the corresponding catalytic efficiencies are compared. NaOH loaded on calcined carbide slag gains the highest catalytic efficiencies. The optimal activated temperature of NaOH loaded on calcined carbide slag is obtained.

Abstract: Based on the physical and chemical properties of carbide slag, the contents of heavy metals in effluent came from carbide slag drying process were studied, and then the composition of exhaust gas emitted from the carbide slag drying process and calcinations process of raw materials prepared with carbide slag was detected, in order to know whether there are harmful or corrosive gases released and the effect of the emissions on the environment and related equipments. The results indicate that the exhaust gases emitted from the calcination process of raw meal prepared with carbide slag is mainly composed of CO₂ and water vapor, and is free from harmful gases. However, a lot of water in carbide slag during the pre-heat and decomposition process under high temperature would accelerate the corrosion of equipments. Simultaneously, a small number of heavy metal ions contained in the carbide slag can cause environmental pollution and sulfides would be adverse to the cement calcination process resulting in the crust blockage of kiln.

Abstract: To study the removal capacity of modified fly ash in wastewater containing mercury ions under different conditions, the carbide slag was added to fly ash, and the pyrogenic process was employed to modify the fly ash. The result indicated that the wastewater had a pH value of 11, the modified fly ash dosage was 2.0 g, the adsorption equilibrium time was 40 minutes, the reaction temperature was 30 °C, the removal rate could reach 97.1%, and the Freundlich-type adsorption isotherm can be used to simulate the adsorption process effectively. The modified fly ash can be used in the removal of mercury-containing wastewater, the overall result of the experiment is satisfactory, which indicates that the modified fly ash has potential value for practical application.

Abstract: This article studied the influence of the caustic soda flakes (CSF) phosphogypsum (Ard) activator on the properties and microstructure of hydration product generated by carbide slag (CS)-flyash (FA) system which used in high-grade highways pavement. Studies have shown that: the main hydration products generated by carbide slag-flyash system are calcium silicoaluminate hydrate (C-A-S-H) and ettringite (AFt), but the reaction of hydration is slow and the content of hydration products is low. However, the caustic soda flakes-phosphogypsum can promote the formation of C-A-S-H and AFt, so can improve the strength and engineering application of the system effectively.

Abstract: In this paper the effects of compound sulfur-fixing agents and compound additives on the sulfur-fixing efficiency were discussed. Thermogravimetric Analysis was used to study the influence of sulfur-fixing agent and additives on the combustion performance. Besides, X-ray fluorescence was applied to research sulfur-fixing mechanism. The results show that, the best sulfur-fixing efficiency was 78.95%, when the ratio of Ca/S was 2.0, experimental temperature was 1000°C, burning time was 20min, the compound sulfur-fixing agents were 80% carbide slag and 20% wastes, the compound additives were 2% iron additives, 6% aluminum additives, 4% sodium additives, 5% silicon additives. The effects of the four additives on the sulfur-fixing efficiency were Al＞Fe＞Si＞Na.

Abstract: A new kind of adsorbent is prepared in the present study, which is expected to capture NOx with high efficiency. NaOH, Ca(OH)2, carbide slag, diatomite, activated alumina are chosen as the major material with a small amount of surfactants and dispersants as the additive. Different recipes were characterized by SEM and N2 adsorption-desorption method. The result showed that the optimum adsorbent has the largest surface area of 95.67m2/g which is Ca(OH)2: NaOH: activated alumina=4:1:1. The test on removal of NOx is conducted. The result showed that the adsorbent is capable of removal efficiency exceeding 98% in 10minutes.

Abstract: Current industrial desulfurization processes involve in economic costs, if carbide slag can be used in those processes, the costs will be reduced and the goal treating waste with waste can be achieved. A mathematic reaction model was built based on the chemical reaction of desulfurization by carbide slag, the overall reaction order n=α+β=1.74, the activation energy Ea=21749.56173J/mol and the frequency factor k0=0.349533643 .

Abstract: A new environment-friendly wall material- the unfired brick is produced by using clay, carbide slag, fly ash and cement as the main raw materials，and certain amount of chemical excitator. The primary mixing ratio is designed on the basis of its mechanical properties and durability. When adopting water curing under normal temperature and atmosphere pressure，the compressive strength，flexural strength and frost resistance of the unfired brick are measured. The results reveal that the optimum mixing ratio for unfired brick is: Carbide slag 30%，fly ash 30%，cement 25% and clay 15%. For the unfired brick formed by vibration with the optimum mixing ratio，the min. compressive strength of each brick is more than 10 MPa, the overall properties meet the requirement as specified in standard JC 239—2001“Fly Ash Brick”.

Abstract: Carbide slag was used as raw materials for the first time to prepare xonontlite whiskers via a hydrothermal route without special instruments and synthesis conditions. And the effect of pH value of emulsion of carbide slag and hydrothermal conditions on removal rate of impurities, morphology and crystallinity of synthesized xonotlite whiskers were explored using ICP, SEM and XRD techniques. The results indicated that the carbide slag after purification could be used to prepare xonotlite whiskers, and different pH values of emulsion of carbide slag had great impact on the removal rate of impurities and morphology of xonotlite whiskers. Xonotlite whiskers with 20-40 μm in length and 100-500 nm in diameter were hydrothermally synthesized at 230 °C for 15 h with using silicic acid as kiesel material.