Evaluation of regional water resources carrying capacity based on binary index method and reduction index method

Based on the regional water resources carrying capacity(WRCC)evaluation principles and evaluation index system in the National Technical Outline of Water Resources Carrying Capacity Monitoring and Early Warning(hereafter referred to as the Technical Outline),this paper elaborates on the collection and sorting of the basic data of water resources conditions,water resources development and utilization status,social and economic development in basins,analysis and examination of integrity,consistency,normativeness,and rationality of the basic data,and the necessity of WRCC evaluation.This paper also describes the technique of evaluating the WRCC in prefecture-level cities and city-level administrative divisions in the District of the Taihu Lake Basin,which is composed of the Taihu Lake Basin and the Southeastern River Basin.The evaluation process combines the binary index evaluation method and reduction index evaluation method.The former,recommended by the Technical Outline,uses the total water use and the amount of exploited groundwater as evaluation indices,showing stronger operability,while the latter is developed by simplifying and optimizing the comprehensive index system with greater systematicness and completeness.The mutual validation and adjustment of the results of the above-mentioned two evaluation methods indicate that the WRCC of the District of the Taihu Lake Basin is overloaded in general because some prefecture-level cities and city-level administrative divisions in the Taihu Lake Basin and the Southeastern River Basin are in a severely overloaded state.In order to explain this conclusion,this paper analyzes the causes of WRCC overloading from the aspects of basin water environment,water resources development and utilization,water resources regulation and control ability,water resources utilization efficiency,and water resources management.

Study on carbon emission calculation method and carbon reduction indexes of urban building stock

Carbon emissions associated with buildings are a major source of urban emissions. To put forward the methods and strategies to curb carbon emissions from urban building stock, it is not only necessary to establish a carbon emission calculation method for fine statistical analysis, but also to evaluate carbon emissions of urban planning schemes with applicable indexes. Currently,researches mainly focus on carbon emissions of individual buildings. When expanded to urban building stock, the calculation faces the lack of basic data, inadequate spatial analysis and unspecific carbon reduction indexes. Therefore, this study proposes a bottom-up calculation method for urban building stock, conducts spatial analysis based on carbon balance of urban grids, reveals the coupling mechanism between urban carbon reduction indexes and grid carbon emissions, and systematically establishes a carbon-reduction-oriented urban planning method that comprises calculation, analysis and evaluation, which is applied to Xi'an,China. This study provides a theoretical reference for cities to formulate carbon reduction targets and implement planning strategies by evaluating and predicting carbon emissions from urban building stock.

Production of titanium powder by metallothermic reduction of TiO2 in cold pressed pellets

In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO2)in the cold pressed pellets were conducted by metallothermic reduction with an indirect contact method.This paper focuses on discussing the mechanism of the reduction process and the relationships of RM(a revised reduction index)with reduction temperature,reduction time,and mole ratio of TiO2 to CaCl2(nTiO2/nCaCl2)in the pellets.The results show that metallic Ti was obtained from the reduction of TiO2 in the pellets by calcium(Ca)vapor;pellets were reduced homogenously and Ca vapor diffused into the porous pellets by Knudsen diffusion or the mixing diffusion of molecular diffusion and Knudsen diffusion at 1273 K;RM increased with the increases of temperature and reduction time and was 96.34%when TRedu=1273 K,tRedu=6 h,and nTiO2/nCaCl2=4;the reasonable nTiO2/nCaCl2 value is 3−5 for the pellets with enough strength and high RM.

Effect of B2O3 addition on oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets with simulated coke oven gas

The oxidation induration and reduction swelling behavior of the chromium-bearing vanadium titanomagnetite pellets (CVTP) with B2O3 addition were investigated. Besides, the reduction swelling index (RSI) and compressive strength (CS) of the reduced CVTP were also examined using the simulated coke oven gas (COG). The results suggested that the CS of CVTP was increased from 2448 to 3819.2 N, while the porosity of CVTP was decreased from 14.86% to 10.03% with the increase in B2O3 addition amounts. Moreover, the B2O3 mainly existed in the forms of TiB0.024O2 and Fe3BO5 in both CVTP and the reduced CVTP. Specifically, the CS of the reduced CVTP was elevated from 901 to 956.2 N, while the RSI was reduced from 5.87% to 3.81% as the B2O3 addition amounts were increased. Taken together, B2O3 addition would facilitate the aggregation and diffusion of metallic iron particles, which contributed to reducing the formation of metal iron whiskers and weakening the reduction swelling behavior.

Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties of composite burden

In order to reduce the materials cost of COREX ironmaking process,sinter has been introduced into the composite burden in China.This work explored the reducing process of sinter in COREX shaft furnace to clarify its reduction properties change and then the effect of sinter proportion on metallurgical performance of composite burden was investigated.The results show that the reducing process of sinter in COREX shaft furnace was basically same with that in blast furnace but sinter seems like breaking faster.Under reducing condition simulated COREX shaft furnace,sinter possessed the worst reduction degradation index(RDI)and undifferentiated reduction index(RI)compared with pellet and iron ore lumps.Macroscopic and microscopic mineralogy changes indicated that sinter presents integral cracking while pellet and lump ore present surface cracking,and no simple congruent relationship exists between cracks of the burden and its ultimate reduction degradation performance.The existence of partial metallurgical performance superposition between composite and single ferrous burden was confirmed.RDI_(+6.3)≥70%and RDI_(+3.15)≥80%were speculated as essential requirements for the composite burden containing sinter in COREX shaft furnace.

Effect of pyroxenite and olivine minerals as source of MgO in hematite pellet on improvement of metallurgical properties

Pelletization of hematite ore requires high fineness and very high induration temperature（~1325 ℃） owing to its poor diffusion bonding unlike magnetite ore. Further, high-alumina hematite pellets show very high reduction degradation index（RDI） during low temperature（500-650 ℃） reduction due to their volume expansion and lattice distortion. Noamundi（India） hematite ore contains very high Al2O3（2.3%） with adverse ratio of alumina to silica（~2） for which, it shows very high RDI. In this work, the acid pellets prepared from Noamundi ore fines of optimum Blaine fineness show good cold crushing strength（CCS）. However, it shows very high RDI（77%）. In order to reduce RDI, Mg O in form of two different gangue-containing fluxes, such as pyroxenite and olivine in varying quantities has been added. The optimum requirement and performance of these fluxes has been examined and compared. Both pyroxenite and olivine fluxed pellets show significant lowering of RDI（26% and 23%, respectively） and improvement of other properties, viz CCS, swelling indices etc with good reducibility（70%-77%）. Finally, a good quality acidic hematite pellet was developed from high-alumina ore without using any lime which is very important charge material in combination of basic sinter in blast furnace.

Preparation of sinter with low reduction degradation index for COREX reduction in a high proportion

The sinter with low reduction degradation index(RDI)for COREX reduction was prepared by separated granulation sintering process.The results illustrate that the productivity and tumble index are attained to be 1.64 t m^(-2)h^(-1)and 59.25%,respectively,in pot tests under the optimal conditions.Under the reducing condition simulating COREX shaft furnace,RDI_(+6.3 mm),RDI_(+3.15 mm),and reducibility index of the sinter reach 63.05%,81.52%,and 83.65%,respectively.Compared with traditional sintering process,the productivity rose by 14.69%,and RDI_(+6.3) mm and RDI_(+3.15) mm were increased by 157.54%and 32.70%,respectively.In addition,as the proportion of sinter reached 60%,RDI_(+6.3 mm)and RDI_(+3.15 mm)of comprehensive burden were achieved to be 73.39%and 84.28%,respectively,which could completely meet the requirement of COREX shaft furnace for RDI.The mechanism was demonstrated that the more silicoferrites of calcium and aluminum and silicate phase occurred as well as magnetite,and the amount of Fe_(2)O_(3)decreased substantially in the sinter by separated granulation sintering process.Hence,the low-temperature reducing stress is restrained,with the increase in sinter strength.

Effect of Ca-Fe oxides additives on NOx reduction in iron ore sintering

As the emission control regulations get stricter,the NO;reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain.The NOxemissions from the sintering machine account for 48% of total amount from the iron and steel industry.Thus,it is essential to reduce NO;emissions from the sintering machine,for the achievement of clean production of sinter.Ca-Fe oxides,serving as the main binding phase in the sinter,are therefore used as additives into the sintering mixture to reduce NOxemissions.The results show that the NO;reduction ratio achieves 27.76% with 8% Ca-Fe oxides additives since the Ca-Fe oxides can advance the ignition and inhibit the nitrogen oxidation compared with the conventional condition.Meanwhile,the existence of Ca-Fe oxides was beneficial to the sinter quality since they were typical low melting point compounds.The optimal mass fraction of Ca-Fe oxides additives should be less than 8%since the permeability of sintering bed was significantly decreased with a further increase of the Ca-Fe oxides fines,inhibiting the mineralization reaction of sintering mixture.Additionally,the appropriate particle size can be obtained when mixing an equal amount of Ca-Fe oxides additives of-0.5 mm and 0.5-3.0 mm in size.

Washing out heavy metals from contaminated soils from an iron and steel smelting site

Washing is a promising method for separating contaminants bound to the particles of soil ex-situ by chemical mobilization. Laboratory batch washing experi- ments were conducted using deionized water and varying concentrations of oxalic acid, citric acid, tartaric acid, acetic acid, hydrochloric acid and ethylenediaminetetra acetic acid （EDTA） to assess the efficiency of using these chemicals as washing agents and to clean up heavy metals from two heavily polluted soils from an iron and streel smelting site. The toxicity reduction index and remediation costs were analyzed, and the results showed that the soils were polluted with Cd, Pb and Zn. Hydrochloric acid and EDTA were more efficient than the other washing agents in the remediation of the test soils. The maximum total toxicity reduction index showed that 0.5 mol·L^-1 hydro- chloric acid could achieve the remediation with the lowest costs.

Effect of Hydrogen Addition on Low Temperature Metallurgical Property of Sinter

Hydrogen-enrich iron making process is certainly to be an effective method to reduce greenhouse gases emission.However,the effect of hydrogen addition on the low temperature metallurgical property of sinter is still unclear.A detailed investigation was performed on the above topic.The results are as follows.When CO is partially replaced by H2,the RDI〈3.15（RDI〈2.8） of sinter decreases with the increase of the H2 content;when the content of H2 increases,the CO,CO2 and N2 decrease proportionally,in this case,RDI〈3.15（RDI〈2.8） of sinter increases with the increase of H2 content;the value of RDI〈3.15（RDI〈2.8） basically depends on the reduction index（Ri）.The experimental data of RDI〈2.8 based on Japanese industrial standard（JIS） are a little higher than the data of RDI〈3.15 based on Chinese industrial standard（CIS） in the same condition.In addition,for part of CO is replaced by H2：RDI〈2.8=3.38394＋1.1585 RDI〈3.15;for other gases,except H2,are decreased proportionally：RDI〈2.8=17.39678＋0.42922 RDI〈3.15

Computational Insights into Interactions between Ca Species and α-Fe_2O_3(001)

CaC12 can be sprayed onto sinter surface, which can improve the low temperature reduction degradation index （RDI＋3.15） of sinter. This has been recognized; however, there are various opinions on the inhibition mechanism of it. At the same time, the corrosion of C1 element on equipment is very serious. First-principle calculations based on density functional theory were performed to investigate the binding mechanisms of calcium species on a a-Fe2 03 （0 0 1） surface. This is crucial in demonstrating the role of the CaC12 on improving the low temperature reduction degrada tion index. It has been determined that C1 could greatly increase the adsorption of the vacuum layer for the Ca/Fe2 03 system and the relaxation produced by adsorption made bond length decrease, bond energies increase and structure compact. Those are the main reasons that inhibiting the reduction disintegration of sinter.

Sintered Ore Sprayed by Acid and Alkaline Waste Water Resulted From Cold Rolling

In order to prevent the powdering of a sintered ore from influencing the smooth operation of a blast furnace,the conventional way to deal with it is that the CaCl2 solution is prepared by tap water,and then the solution is sprayed onto the sintered ore for improving its RDI（low temperature reduction degradation index）.The CaCl2 solution prepared by adding acid and alkaline waste water resulted from cold rolling is sprayed onto the sintered ore to improve its RDI.The values of RDI＋6.3 and RDI＋3.15 of the sintered ore which is sprayed by the CaCl2 solution with the CaCl2 concentration of 3.5%（mass percent） are increased by 17.5% and 11.63%,but the index of RDI-0.5 is decreased by 3.1% when the spraying amount of the solution is making up 0.5% of the total sintered ore sprayed in comparison with those of the sintered ore which is not sprayed by using the CaCl2 solution.Experimental results show that after the CaCl2 solutions prepared by adding the acid and alkaline waste water are sprayed on the sintered ore,RDI of the ore can be remarkably improved and therefore another way for recycling acid and alkaline waste water can be available,by which both cost for treating waste water and cost for producing a sintered ore can be decreased and environment is free of pollution by harmful substances in the waste water.