Advanced Materials Research Vols. 194-196

Abstract: This study was to investigate the hydration characteristics and cementious properties of pyrolytic steel slag（PSS）. Initially, PSS pastes were made to determine the hydration characteristics of PSS and the results indicated that the hydration activity of PSS with 6.4% gypsum content was stronger than that of paste with pure PSS. Afterwards, compressive strength of mortars were tested and the results showed that cement mortars with 0% to 30% replacement of PSS satisfied the requirements of activity index class of 80% at 28 days. As an activator, gypsum was supiror to calcium hydroxide in performance.

Abstract: In this paper, we concluded that, in order to make good experiment effect, kitchen waste temperature rising rate should be at least 20°С / min. Taking in account experiment effect and experiment energy consumption, a pyrolysising technology is designed to change the kitchen waste's temperature rising rate in phases. At last, a set of mechanical equipment is designed to solve kitchen waste problem efficiently as well as produce bio-oil and other chemical raw materials. The result of prototype experiment shows the feasibility of the kitchen waste disposal equipment and technology.

Abstract: The sintering performance of corundum-silicon nitride castable with brown corundum dust powder added was studied in this paper to provide a theoretical basis for the reuse of this waste powder. Waste powder, corundum, silicon nitride and silicon carbide were used as raw materials in this experiment. The sintered samples were measured routine physical property, and analyzed the microstructure of samples by SEM. Results shows that the addition of dusting powder could promote the sintering performance of non-oxides and the formation of Sialon, and improve the physical properties of samples. But when dusting powder added over 6% of the total, there are too much liquid phases, which will reduce the fire resistance performance at high temperature, so the appropriate added amount of dusting powder should be less than 6%.

Abstract: High-strength and micropore lightweight bauxite aggregate was fabricated by low grade raw bauxite powder, aluminium hydroxide powder and organic polymer (OP). OP was used as consolidator, binder and pore former and aluminium hydroxide was used as pore former. The influence of OP and aluminium hydroxide content on the property of the samples was studied. The phase composition and the microstructure of the sintered samples were characterized by XRD, SEM and the pore size distribution was measured by mercury porosimety. The results demonstrate that the bulk density of the samples decreases linearly and the apparent porosity of the samples increases gradually with the addition of OP. The lowest density reached 1.13g/cm³ when adding 35% OP and 10% Al(OH)₃. The average pore size is around 5μm, and increases with the addition of OP increased. The XRD showed the main phase of the sample is mullite and some little amount of corundum.

Abstract: A promising option for long-term storage of CO₂ is to fix CO₂ by industrial solid wastes, such as basic oxygen furnace (BOF) steelmaking slag. It is advantage to use BOF steelmaking slag to fix CO₂, such as large volume of BOF steelmaking slag, low price of raw materials, close to the CO₂ emission sources, and no secondary pollution. It is of great significance to the CO₂ emissions reduction and solid waste disposal in the ironmaking and steelmaking plant. In this paper, the leaching process, impurities removing and carbonation of steelmaking plant waste slag were studied at ambient pressure. The results show that Ca²⁺ leaching mainly occurs at the beginning 60min in the leaching process. The Ca²⁺ leaching ratio can reach about 45% with the leachant of 2mol/L HAc, leaching temperature of 30°C and solid-liquid ratio of 1:20. Moreover, it can effectively remove Mg²⁺, Al³⁺ and Fe³⁺ by adding small amounts of NaOH and triethanolamine in the leaching solution, and thereafter, high purity CaCO₃ products can be obtained through the carbonation process.

Abstract: Selective Reduction of Cold Bound Pellet – Smelting Separation – Ferroniobium Smelting Technology’ is an effective enrichment and extraction process of Nb from iron tailings of Bayan Obo deposit. Theoretical basis for the thermodynamic feasibility of smelting separation process was provided aiming at the thermodynamic problems in the process by analyzing and calculating through thermodynamic diagram, isothermal equation, and the calculation model of activity for slag system of CaO–SiO₂–FeO–CaF₂–TiO₂–La₂O₃–Nb₂O₅. The results show that the separation of iron and Nb in arc furnace by smelting separation is feasible. In smelting separation process the valence state of Nb in slag is mainly pentavalent and the activity coefficient of Nb₂O₅ is 0.4×10^-5~5.8×10^-5. The distribution ratio of Nb between slag and molten iron decreases with increasing temperature or [%C], whereas increases with increasing basicity (CaO/SiO₂). The temperature should be controlled under 1450°C, the basicity (CaO/SiO₂) should be elevated appropriately, and [%C] should be controlled under 3.6% at the final stage of smelting separation process.

Abstract: Activated carbons (ACs) from petroleum coke by microwave heating KOH activation are treated by microwave to investigate the effect of microwave−treatment power on AC properties. The electrochemical properties of AC electrodes for supercapacitors were investigated by cyclic voltammetry, constant current charge−discharge and electrochemical impedance spectroscopy. The results showed that specific surface area (SBET) and total pore volume of microwave−treated ACs, specific capacitance and energy density of microwave−treated AC electrodes decreased. The electrical conductivity and stability of AC electrodes for supercapacitors were improved. Fast microwave−treatment is an efficient method to obtain suitable ACs for supercapacitors.

Abstract: In this research, shrimp waste was fermented with 3 species of symbiotic lactic acid bacteria, namely Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus bulgaricus. The ingredient changes occurring in the fermentation process were investigated. Results showed that the production of lactic acid in the fermentation process was remarkably improved, with the pH decreasing rapidly to 4.25 within 8 h, the lowest pH reaching 3.22, and the titratable acidity reaching 25.0 mmol/100ml. The improved acidic environment promoted the removal of calcium and protein, with 91.3% calcium, 97.7% protein and 32.3% carotenoid removed from shrimp waste after 168 h fermentation. The putrefaction was effectively prevented and the TVBN level was low throughout the whole process. Glucose was consumed rapidly in the earlier phase of the fermentation; about 69.4% glucose was consumed in the initial 24 h. The consumption of glucose was in well accordance with the growth of lactic acid bacteria, the removal of calcium and the increasing of titratable acidity. The amino nitrogen content kept increasing within 48 h, thereafter it came to decrease. 88.4% of peptides in the hydrolysate ranged between 1000 ~ 10000 Da, 10.2% smaller than 1000 Da, and 3.44% larger than 10000 Da.

Abstract: The amorphous silica was prepared from the alkali wastewater rich in Na₂O•nSiO₂ produced in manufacturing process of zirconium oxychloride (ZrOCl₂). The composition and microstructure of amorphous silica were studied by X-ray diffraction, X-ray fluorescence and scanning electron microscope, respectively. The results showed that the amorphous silica was mainly composed of uncrystallized substance, and the silica content was 96.4%. Its whiteness was 97.5% and the particle size was between 100nm and 200nm without agglomeration. The specific surface area of the amorphous silica was 531.9 m²/g, and its pore volume and diameter were 0.945 cm³/g and 4.94 nm, respectively.

Abstract: This paper aims to study the feasibility of two solid waste which are steelmaking slag and fly ash as desulfurization and denitration absorbents by microwave. Under the optimal operating conditions, the removal efficiencies of 70.9% and 69.6% are achieved for SO₂ and NOX respectively. The microstructure of before and after the adsorbent reaction are analyzed by SEM. Base on the experiment research, he mechanisms of simultaneous desulfurization and denitration are investigated in this paper. The research provides a new approach to resource recycling of steelmaking slag and fly ash. And the result has great significance to recycle solid waste and preserve the sustainable development of industrial economy and environment.