Preparation of Granulated Adsorption Material of Water-quenched Slag/rectorite Composite for Removal of Cu(Ⅱ)Ions from Copper Smelter Wastewater

The preparation of granulated adsorption material of water-quenched slag/rectorite composite and the treatment of Cu （ Ⅱ ）-containing copper smelter wastewater with the adsorption material were studied. The experimental results showed that under the conditions with the mass ratio of water-quenched slag to rectorite of 1：1, 10% additive of industrial starch （IS）, and 50% water, and a calcination temperature of 400 ℃, the granulated adsorption material prepared had a density of 1.06 kg/m^3, a porosity of 62.29%, water absorption rate of 58.82%, and compressive strength of 2.22 MPa. The efficiency of wastewater treatment was the best, whereas the rate of spallation loss was low. Under the conditions of natural pH, with the addition of the granulated adsorption material of 0.05 g/mL, a reaction time of 40 minutes, and temperature of 25 ℃, the efficiency of the granulated adsorption material for the removal of Cu （ Ⅱ ） ions from the copper smelter wastewater attained 98.2%, and the quality indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard （GB8978-1996）. The reclamation of the used granulated adsorption material was carried out by de-sorption of the Cu （ Ⅱ） ions from the surface with 1 mol/L sodium chloride solution. The de-sorption rate was 96.4%, and the adsorption material can be reused many times to treat copper smelter wastewater.

Influence of carbon content on microstructure and mechanical properties of Mn13Cr2 and Mn18Cr2 cast steels

In this paper, a comparison study was carried out to investigate the influence of carbon content on the microstructure, hardness, and impact toughness of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The study results indicate that both steels' water-quenched microstructures are composed of austenite and a small amount of carbide. The study also found that, when the carbon contents are the same, there is less carbide in Mn18Cr2 steel than in Mn13Cr2 steel. Therefore, the hardness of Mn18Cr2 steel is lower than that of Mn13Cr2 steel but the impact toughness of Mn18Cr2 steel is higher than that of Mn13Cr2 steel. With increasing the carbon content, the hardness increases and the impact toughness decreases in these two kinds of steels, and the impact toughness of Mn18Cr2 steel substantially exceeds that of Mn13Cr2 steel. Therefore, the water-quenched Mn18Cr2 steel with high carbon content could be applied to relatively high impact abrasive working conditions, while the as-cast Mn18Cr2 steel could be only used under working conditions of relatively low impact abrasive load due to lower impact toughness.

Influence of carbon content on wear resistance and wear mechanism of Mn13Cr2 and Mn18Cr2 cast steels

By means of impact abrasion tests, micro-hardness tests, and worn surface morphology observation via SEM, a comparison research based upon different impact abrasive wear conditions was conducted in this research to study the influence of different carbon contents(1.25 wt.%, 1.35 wt.%, and 1.45 wt.%) on the wear resistance and wear mechanism of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The research results show that the wear resistance of the Mn18Cr2 cast steel is superior to that of the Mn13Cr2 cast steel under the condition of the same carbon content and different impact abrasive wear conditions because the Mn18Cr2 cast steel possesses higher worn work hardening capacity as well as a more desirable combination of high hardness and impact toughness than that of the Mn13Cr2 cast steel. When a 4.5 J impact abrasive load is applied, the wear mechanism of both steels is that plastic deformation fatigue spalling and micro-cutting coexist, and the former dominates. When the carbon content is increased, the worn work hardening effect becomes increasingly dramatic, while the wear resistance of both steels decreases, which implies that an increase in impact toughness is beneficial to improving the wear resistance under severe impact abrasive wear conditions. Under the condition of a 1.0 J impact abrasive load, the wear mechanism of both steels is that plastic deformation fatigue spalling and micro-cutting coexist, and the latter plays a leading role. The worn work hardening effect and wear resistance intensify when the carbon content is increased, which implies that a higher hardness can be conducive to better wear resistance under low impact abrasive condition.

Effect of Cooling Rate on the Formation and Morphology of (W,V)Cx in VC-doped WC–Co Cemented Carbide

The grain growth retardation mechanism and the effect of cooling rate on VC-doped WC–Co cemented carbides were investigated in this work.WC–30Co and WC–30Co–VC were prepared by powder metallurgy,liquid-phase sintering at 1400 ℃ and followed by water quenching（[150 ℃/s） or furnace cooling（＊0.083 ℃/s）.Based on the results of electron probe microanalysis（EPMA）,we found that WC concentration in the Co binder was independent of VC doping during liquid-phase sintering,hence barely contributing to the retardation of WC grain growth.In contrast,the（W,V）Cx phase formed at the WC/Co interfaces played a major role in retarding WC grain growth during liquid-phase sintering.The effect of cooling rate on the morphology of（W,V）Cxwas revealed by high-resolution transmission electron microscopy（HRTEM） and energy-dispersive spectroscopy（EDS）.In the water-quenched WC–30Co–VC,（W,V）Cxprecipitates were found as thin layers at the WC/Co interfaces.In contrast,both thin layers of similar thickness and nanoparticles of（W,V）Cx were observed in the furnace-cooled counterpart.These observations listed above suggested that thin（W,V）Cxlayers were stable structures effectively suppressing the growth of WC grains and their thickness remained independent of the cooling rate.The（W,V）Cxnanoparticles,however,may be inhibited through rapid cooling,ensuring the VC-doped WC–Co cemented carbides desired toughness.

Synthesis of highly effective absorbents with waste quenching blast furnace slag to remove Methyl Orange from aqueous solution

Water quenching blast furnace slag （WQBFS） is widely produced in the blast furnace iron making process. It is mainly composed of CoO, MgO, A1203, and SiO2 with low contents of other metal elements such as Fe, Mn, Ti, K and No. In this study, WQBFS was treated with grinding, hydrochloric acid acidification, filtration, filtrate extraction by alkali liquor and a hydration reaction. Then BFS micropowder （BFSMP）, BFS acidified solid （BFSAS） and BFS acid-alkali precipitate （BFSAP） were obtained, which were characterized by X-ray diffrac- tion, scanning electron microscopy, X-ray fluorescence and Brunauer-Emmet-Teller （BET） specific surface area. The decoloration efficiency for Methyl Orange （MO） was used to evaluate the adsorptive ability of the three absorbents. The effects of adsorptive reaction conditions （pH and temperature of solution, reaction time, sorbent dosage and initial concentration） on MO removal were also investigated in detail. The results indicated that BFSAP performed better in MO removal than the other two absorbents. When the pH value of MO solutions was in the range 3.0-13.0, the degradation efficiency of a solution with initial MO concentration of 25 mg/L reached 99.97% for a reaction time of 25 rain at 25℃. The maximum adsorption capacity of BFSAP for MO was 167 mg/g. Based on optimized experiments, the results conformed with the Langrnuir adsorption isotherm and pseudo-second-order kinetics. Among inorganic anions, SO2- and PO4- had significant inhibitory effects on MO removal in BFSAP treatment due to ion-exchange adsorption.