| Objective Study of the properties and distribution of particulates in core-making,moulding,casting and melting,pouring and cast shakeout in a wear-resistant Ltd.Analyzed the characteristics of the particles and the contact concentration of the workers.MethodChoosed a wear-resistant parts Co.Ltd.for the research site,collecting dust and chemical occupational hazards of historical data,calculated the concentration of the mean,range,analysis characteristics;supplemented dispersion,respiratory dust concentration data,1Onm?420nm particle size range of fine particles and ultrafine particulates number concentration and data of detection the concentration of 12 metals and their compounds in total dust and respirable dust,including chromium,cadmium,manganese,aluminum,lead,copper,zinc,magnesium,nickel,iron,molybdenum and titanium.Data was input with EpiData 3.1 software and Office Excel 2007 software for windows.SPSS 21.0 software was used for statistical analysis of data.Result1.Dispersion The proportion of particle size less than 2pm in Core making,molding,melting,pouring and cast shakeout was more than 50%,the proportion of particles less than 5?m accounted for more than 75%,the number of particles less than 5?m in pouring highly reached 96%.2.Concentration The highest concentration of silica total dust was in molding.The highest concentration of total dust in the molding air reached 12.80 mg/m3.The highest concentration of silica respirable dust was in melting,reached 1.03mg/m3.The ratio of respirable dust concentration to total dust concentration in 5 jobs was less than 40%.3.The metals and their compounds in total dust and respirable dust Chromium,cadmium,manganese,aluminum,lead,copper,zinc,magnesium,iron,nickel,molybdenum,titanium 12 kinds of metals and their compounds(Mn was accouted by MnO2).In addition to cadmium and its compound was lower than detected concentration,the other 11 kinds of metals and their compounds were present in different concentrations.The concentration of iron and its compounds was the highest,and the concentration of total dust and respirable dust was in the range of 53×10-3mg/m3?490.0?g/m3 and 19.0?g/m3?190.0?g/m3.The concentration detection results of copper and its compounds the lowest total dust and respirable dust concentrations were in the range of 0.6?g/m3?7.8?g/m3 and 0.6?g/m3?2.1?g/m3?The concentration detection results of nickel,chromium,zinc,manganese,lead and its compounds for a minimum was 0.6?g/m3,the highest was 28.0?g/m3.Iron and its compounds,aluminum and its compounds and magnesium and its compounds in the total dust,respirable dust accounted for the highest proportion,all more than 1%.The proportion of lead and its compounds and copper and its compounds in the total dust and respirable was the last two.The proportion of total metal and its compound of core-making,moulding,pouring and cast shakeout in the respirable dust was more than in the total dust.4.Ultrafine and fine particles The largest concentration of ultrafine particles was in the cast shakeout,the average was 21.08×104P/cm3,the range was 7.04×104P/cm3?44.13×104P/cm3.The melting was the smallest,mean was 5.13×104P/cm3,the range was 2.89×104P/cm3?8.87×104P/cm3.The total amount of ultrafine particles and fine particles(10nm?420nm)was the largest concentration of the post cast shakeout,the average was 21.78×104P/cm3,the range was 7.88×104P/cm3?45.08×104P/cm3,the melting position was the smallest,the average is 5.65×104P/cm3,the range was 3.04×104P/cm3?11.45×104P/cm3.The total concentration of ultrafine particles and fine particles(10nm?420nm)in the rest room exceeded that of the environmental background.5.The chemical hazards The chemical hazards of the workplace include chromium oxide,manganese dioxide,molybdenum and its compounds,nickel and its compounds,zinc oxide,carbon monoxide,nitrogen dioxide,triethylamine,phenol,naphthalene,diphenylmethane diisocyanate(MDI),benzene,toluene and xylene etc.The results of molybdenum and its compounds in the air of the casting job was up to 1.88mg/m3,and the concentration of MDI in the air of the core operation was as high as 0.155mg/m3.ConclusionIn this study,the maximum concentration of total particle size of the particle size of 10nm?420nm in cast shakeout,core-making,moulding,melting and pouring and the maximum concentration of ultrafine particles was in the cast shakeout.The average was 21.78×104P/cm3,21.08×104P/cm3,the maximum concentration of ultrafine particles reached 44.13×104P/cm3,and the maximum concentration of particles was in the range of 32nm?56nm.The concentration of nickel,chromium,zinc,manganese,lead and their compounds in particles was the lowest,0.6?g/m3,and the highest was 28.0?g/m3.The concentrations of chromium,manganese,aluminum,lead,copper,zinc,magnesium,nickel,molybdenum and titanium and their compounds in total dust respirable dust in proportion,iron,magnesium,and aluminum compounds were accounted for the number of more than 1.0%,lead,copper and its compounds accounted for in the last two.The total metal and its compound content in the respiratory dust of core-making,moulding,pouring and cast shakeout were higher than those in the total dust.The composition of fine particles was complex.The harm of fine particles to workers should be caused by attention of all aspects. |
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