Recovery of zinc and lead by simultaneously leaching from lead slag fuming dust with ammonium chloride solution

The effects of leaching temperature(60−105°C),NH4Cl concentration(3−7 mol/L),liquid/solid ratio(4:1−12:1 mL/g),stirring speed(150−750 r/min),and leaching time(5−90 min)on the leaching rates of Zn and Pb were investigated.The leaching kinetics of Zn-and Pb-rich fuming dust with a NH4Cl solution was also studied.The leaching rates of Zn and Pb respectively reached 98.2%and 75.6%at leaching temperature of 100°C,an NH4Cl concentration of 7.0 mol/L,a liquid/solid ratio of 10:1 mL/g,a stirring speed of 450 r/min and leaching time of 60 min.The kinetics results indicate that the leaching of Zn and Pb conforms to the shrinking unreacted core model and is controlled by the internal diffusion of NH4Cl through the reacted fuming dust layer and external diffusion of NH4Cl through the leaching solution boundary layer,respectively.The apparent activation energies of Zn and Pb are 23.922 and 19.139 kJ/mol,respectively.This study demonstrates that the use of NH4Cl solution,without ammonia,is an environmentally friendly method for simultaneous extracting Zn and Pb from the fuming dust of lead blast furnace slag.

Smoke distribution in naturally ventilated urban transportation tunnels with multiple shafts

The smoke spreading law of urban transportation tunnels with multiple shafts under natural ventilation is studied.A full-scale burning experiment is conducted in an actual tunnel.The study shows that smoke temperatures below the tunnel ceiling reduce rapidly along the longitudinal towards the tunnel exits. A noticeable temperature stratification is observed near the fire source.Most fire smoke is exhausted out of the shafts while the number of the smoke shafts in the downstream is more than that in the upstream.Large eddy simulation LES based on computational fluid dynamics CFD is carried out using the fire dynamics simulator FDS software with parallel processing in which the grid size of the fire-domain is set to be 0.083 m.The simulation results of temperatures under the ceiling the smoke fronts and the shafts＇smoke exhaust or air supply agree reasonably with the experimental data. Further simulations indicate that the decreasing ambient temperature or shaft spacing might reduce smoke temperatures under the tunnel ceiling and increase mass flow rates out of the shafts.This study provides technical scientific evidence and supports for the design and construction of such kinds of tunnels.

Modeling and Simulation Study on Reverse Swirl of Secondary Air in Large Tangentially Fired Boiler

Based on the porosity method and the improved non uniform QUICK scheme, this paper describes a three dimensional computer simulation to predict the flow characteristics in a tangentially fired boiler. The model is applied to a 600?MW boiler modeling under different operating conditions of reverse swirl of secondary air. The numerical results achieve reasonable agreement with experimental data. The calculated results of flow field, the pressure distribution, the relative diameter of tangential circle, angular momentum flux in furnace and the velocity distribution index in horizontal gas pass are analyzed in detail. And then the effects of the reverse swirl of secondary air on flue gas imbalance are discussed. Finally a reasonable operating condition of the reverse swirl of secondary air is presented.

Numerical simulation and disaster prevention for catastrophic fire airflow of main air-intake belt roadway in coal mine—A case study

Coal mine belt fire develops very rapidly and is difficult to control. If not suppressed quickly, a belt fire could easily lead to airflow disorder and undermine the ventilation system. However, belt fire can be prevented effectively by establishing fire airflow control system. In this work, the 5th belt roadway of Kongzhuang coal mine was taken as the object of investigation, where geometrical models of this roadway were established firstly. Then, based on mathematical model of fire smoke flow, the CO volume fraction, smoke density distribution, air temperature and pollutant velocity vector in the roadway before and after taking airflow control measures were simulated by using Fluent software. It can be known from the simulation that with the normal ventilation status in 5th belt roadway, the countercurrent of smoke does not happen when a fire occurs; the roadway's section is almost filled with CO at 10 m downstream from the fire source, and with air velocity getting stable gradually, the CO concentration reaches about 15 %. After taking airflow control measures, the effect range of temperature field which are harmful to the miners decreases from 69 m to 30 m; and the distance of the roadway fully filled with CO is 5 m farther than that before taking measures. Finally, according to the numerical simulation results and the actual condition of the belt roadway, the warning and automatic remote airflow control system with short-circuit method for the 5th belt roadway was designed to guarantee the safety production.

Risk factors for Barrett’s oesophagus and oesophageal adenocarcinoma:Results from the FINBAR study

AIM:To investigate risk factors associated with Barrett's oesophagus and oesophageal adenocarcinoma.METHODS:This all-Ireland population-based case-control study recruited 224 Barrett's oesophagus patients,227 oesophageal adenocarcinoma patients and 260 controls.All participants underwent a structured interview with information obtained about potential lifestyle and environmental risk factors.RESULTS:Gastro-oesophageal reflux was associated with Barrett's [OR 12.0(95% CI 7.64-18.7)] and oesophageal adenocarcinoma [OR 3.48(95% CI 2.25-5.41)].Oesophageal adenocarcinoma patients were more likely than controls to be ex-or current smokers [OR 1.72(95% CI 1.06-2.81)and OR 4.84(95% CI 2.72-8.61)respectively] and to have a high body mass index [OR 2.69(95% CI 1.62-4.46)].No significant associations were observed between these risk factors and Barrett's oesophagus.Fruit but not vegetables were negatively associated with oesophageal adenocarcinoma [OR 0.50(95% CI 0.30-0.86)].CONCLUSION:A high body mass index,a diet low in fruit and cigarette smoking may be involved in the progression from Barrett's oesophagus to oesophageal adenocarcinoma.

Meta-Analysis of Smoking and the Risk of Gastric Cancer among the Chinese Population

OBJECTIVE To reevaluate the effect of tobacco smoking on therisk of developing gastric cancer among the Chinese population.METHODS Thirty articles from the literature both in Chineseand English from January,1988 to present were identified andfrom which adjusted odd ratios(ORs)or relative risks(RRs)werecombined by meta-analysis.Generalized least squares(GLS)fortrend estimation of summarized dose-response data was carriedout.All the analyses were performed using software of STATAversion 10.0.RESULTS Comparing current smokers with subjects who havenever smoked,the summary effect values on gastric cancer witha 95% confidence interval(CI)were 1.67(1.43-1.96)for case-control studies and 1.52(1.17-1.96)for cohort studies,respectively.The combined effect values with a 95%CI for the comparison ofsmoking quantity of current smokers with the referent groupwere 1.41(1.15-1.72)for case-control studies and 1.24(1.02-1.52)for cohort studies,respectively.The combined effect values witha 95%CI for the comparison of accumulative years smoked ofcurrent smokers with the referent group were 1.07(0.89-1.28)for case-control studies and 1.28(0.95-1.74)for cohort studies,respectively.Dose-response meta-analysis showed that the gastriccancer risk will increase 50%(OR=1.50,95%CI:1.34-1.67)witheach 20 cigarette per day increment and increase 14%(OR=1.14,95%CI:1.10-1.18)with each 10 year increment of smoking.CONCLUSION The gastric cancer risk among the Chinesepopulation is significantly associated with tobacco smoking andthe smoking quantity per day.Smoking cessation should be morestrongly advocated.

Reduction of Tobacco Smoking Health Risk Through an Appropriate Media Based Communication Strategy in Uganda

The health impacts of tobacco consumption are well documented and have gained acceptance worldwide. Today, a substantial, preventable burden of tobacco attributable diseases exists in most countries, though in most of the cases, unknown. Smoking accounts for almost half of the deaths in middle age in some regions. In Uganda, translating findings into policy action is slow and involves several stakeholders. It will continue to require support from tobacco control campaign groups. This paper analyses secondary literature on tobacco smoking and later provides an appropriate medium based communication strategy that can be adopted to counteract the persuasive smoking evil adverts of tobacco companies as well as creating awareness among the population of the health impacts caused by smoking.

Research on super-low-ash anthracite preparation

The fundamental question of super-low-ash coal preparation is how to furthest depress high ash component pollution. A jigging process was used to remove high ash refuse and middling, then a high precision heavy medium cyclone was used to further separate near gravity light material. A two-stage heavy medium cylindrical cyclone with the same separation density was used to increase the precision of separation. The feed was de-slimed and fine-grind coal was added with media to improve the stability of the suspension. The pump frequency conversion timing and an air spring were used to steady the cyclone inlet pressure. Based on a series of study and pilot tests, a 1.00 Mt/a (output) commercial separation system with Ep value under 0.015 was built up. Super low ash (Ad≤2.00%) Taixi Anthracite has been put into commercial production.

Estimate the Ventilation Effect from Wire Mesh Screen Assisted Solar Chimney

In 1750s European houses, chimneys are used to remove smoke and dust particle from the fire place to the ambient. At present the applications of chimneys are extended for house ventilation, which is known as solar chimney assisted ventilation system. In this paper, the effect of wire mesh screen on chimney assisted ventilation system is studied and presented. Natural draft chimney integrated with solar heating system that is known as solar chimney, can be used for building ventilation. Number of research works had been conducted on different types of solar chimney to enhance the building ventilation performance. In this study a solar chimney model is designed and modified with wire mesh screens. An electric heating system is installed in the models to replace the solar absorber in the solar chimney. The airflow rates and the exit air temperatures are also measured and compared for normal chimney and modified chimneys under different heat loads. The performances of the chimneys are evaluated to determine the effects of wire mesh screen on the solar chimney. Experimental results indicated the solar chimney model with 0.64 mm × 0.64 mm pore size wire mesh screen at the exit is able to enhance velocity and the exit air temperature are about 54% and 41%, respectively. It has been concluded that the wire mesh screen has significant effect of model solar chimney and is able to enhance the performance.

Simulation study of blast fume diffusion characters of driving face

Based on FLUENT software, studied the blast fume diffusion characteristics of a driving face under 8 situations, and analyzed the influence to fume diffusion of different drift length and different ventilation pipe outlet positions. Through regression analysis, functions of ventilation time to the drift length and ventilation pipe outlet position was obtained.

Design and error estimates of cut tobacco feeding by wind system

The cut tobacco transporting is the absolutely necessarily important tache, Whether the transportation process stability is a direct impact on production quality and manufacturing standards. The wind system is adopted by most tobacco companies because of it caused least disruptive of the cut tobacco structure and the pipe network layout of system is flexible, but the wind system is greater influence by itself, different control methods are caused greater difference of process indicators, for example essence and spice ingredients, moisture proportion and smoke flavor. Based on the above reasons, so we need to design the control method of wind system necessarily, in addition we must checkout the control accuracy opportunely, so that it is satisfied by the actual working conditions.

Development of Three Risk Assessment Models for Deoxynivalenol and Fumonisins B1 ＋ B2 Contents in Maize Kernel

The maximal deoxynivalenol （DON） and fumonisins 131 ＋ B2 （FUM） contents in cereals are dictated by the European regulation 1126/2007. The direct measurement of these mycotoxins is a tedious and expensive process. Our study is based on an alternative tool： near infrared spectroscopy. Different models were developed on 374 maize samples to predict their DON and FUM contents. Several parameters have been determined and used in a multivariate data analysis. Three models were developed： （1） a classification model based on Discriminant Factor Analysis （DFA）, （2） a linear model based on ANalysis of COVAriance （ANCOVA） and （3） a Partial Least Squares Discriminant Analysis model （PLS-DA）. Firstly, the performances of the DFA model for assessing DON and FUM risk were similar： 69 and 72% of the validation samples were respectively well classified. In the second part, the performances of the ANCOVA model for DON were higher than for FUM. The r2 was worth respectively 0.85 and 0.69. In the last part, the performances of the PLS-DA models were better for FUM than for DON. These results show that an evaluation of the mycotoxin risk is possible by analyzing selected kernel parameters measurable by secondary analytical such as near-infrared spectroscopy. Further work is needed to improve the models, adding more samples and using non linear approaches.

Exhaust Ventilation through a Solar Chimney： A Response to High Hermeticity in Welfare Housing

This research reports on potentiality in the solar chimney as an exhaust ventilation device through a hypothetical statement that convenient weather conditions exist on sub-humid warm climate to enhance the performance ofa SC （solar chimney）, in order to increase ventilation to dissipate metabolic heat from inhabitants of airtight buildings. The methodology used in this research integrates the use of simplified mathematical models that predict in a semi-empirical way a potential volume flow through estimation of kinetic power generation, by natural circulation and stack effect in a typical covered-plate air solar collector. The study was carried out during the warm month of April, an important warm season for Colima, where the prevailing wind is about 6.8 m/s, the average temperature of maximums and minimums oscillates between 15.4℃and 34.4 ℃ with average relative humidity of 65% according to national weather service. A scale model of the SC was installed on environmental chambers. The results showed that this device is capable of generating ventilation conditions around light breeze parameters near between 0.6 m/s and 1.5 m/s width, a better performance at day in 45% approximately than the night values, making ventilation rates up 0.24 ACH （air changes per hour） as average air change rate.

Calculation of CO Behavior in the Platform for Deeply Underground Subway Station with Different Fire Strengths

Effect of different fire strengths on the smoke distribution in the subway station is investigated. Shin-Gum-Ho station （line #5） in Seoui is selected as a case study for variation of CO （carbon monoxide） distribution caused by the fire in the platform. The ventilation in the station is set to be an air supply mod in the lobby and an air exhaustion mod in the platform. One-side main tunnel ventilation （7,000 m3/min） is applied to operate in the tunnel. The fire is assumed to break out in the middle of train parked in the platform tunnel. Two kinds of fire strength are used. One is 10 MW and the other is 20 MW. Ventilation diffusers in the station are modeled as 317 square shapes ＆ four rectangular shapes in the lobby and platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for parallel computation. Large eddy simulation method is applied to solve the momentum equation. The behavior of CO is calculated according to different fire strengths and compared with each other.

Chewing substances with or without tobacco and risk of cardiovascular disease in Asia:a meta-analysis

Objective:To assess whether people who ever use any form of chewing substance in Asia are at increased risk of cardiovascular disease(CVD).Methods:PubMed and ISI Web of Science were searched for relevant studies,with no limitation on language or study year.Studies were included if they provided quantitative estimate of the association between ever use of chewing substance and the occurrence of CVD.Two authors independently implemented inclusion criteria,abstracted study characteristics,and performed meta-analysis.Summary relative risks were estimated on the basis of a random effect model.We used Q statistic and Egger's test to examine heterogeneity across studies and potential publication bias,respectively.Results:Eight eligible studies were included.The relative risk of CVD for ever using chewing substances with or without tobacco was 1.26(95% confidence interval(CI) 1.12-1.40),which was unchanged when restricted to cohort studies [1.25(1.08-1.42)] or cohort studies in Taiwan [1.31(1.12-1.51)].The summary relative risk for ischemic heart disease was 1.27(1.02-1.52),and was lowered to 1.26(0.85-1.67) after exclusion of a cross-sectional study.The overall relative risk for cerebrovascular disease was 1.32(1.08-1.56).On the basis of the Taiwan data,the summary relative risk of CVD for betel(Areca catechu) chewing was 1.30(1.17-1.44).Data on dose-response were limited to betel chewing in Taiwan,suggesting a relationship between risk of CVD and cumulative exposure.Two large cohorts in Taiwan reported a greater risk of CVD with betel chewing than with smoking.Conclusions:An association was detected between betel chewing with or without tobacco and the risk of CVD.Betel chewing may impose a greater CVD risk than smoking.More effort is needed in developing betel chewing cessation programmes.The relationship between betel chewing and subgroups of CVD requires further investigation.

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