Study On The Preparation And Certifying Value Method Of Internal Control Reference Material For Tungsten Concentrate And Roasted Molybdenum Concentrate

One tungsten concentrate and one roasted molybdenum concentrate was prepared.A method of the determination of coexisting elements in tungsten concentrate using microwave digestion and ICP-AES was established.The application,prospect and the principal analysis method for tungsten concentrate and roasted molybdenum concentrate was surveyed.Classical chemical methods such as gravimetric method and titration are still the main method for the analysis for the main and constant elements content in tungsten and molybdenum concentrate.Because of the advantages such as simultaneous analysis of multiple elements,easy way to operate and the high accuracy and precision,ICP-AES and ICP-MS become more and more suitable for the analysis of impurity elements in ore samples.A new method of simultaneous determination of major coexisting elements such as As,Cu.Mn.Mo,P,Si,Ba in tungsten concentrates using microwave-assisted acid digestion and inductively coupled plasma optical emission spectrometry(ICP-OES)was established.The results show that(1)With mixed HCL-HNO3-HF(5+3+2)as digestion solution,microwave digestion heated to 160℃ and holding for 10 min,.the solution is clear and suitable for immediate determination,non separation of tungsten matrix needed;(2)The optimum conditions of the instrument are RF power 1200W,nebulization gas flow 0.75L/min,auxiliary gas flow 1.5L/min,cooler gas flow 15L/min,view distance 10mm and pump flow 2.0L/min;(3)Integrated signal to noise ratio,spectral line interference and other factors,the optimum analysis lines are chosen:As(193.696nm),Cu(324,754nm),Mn(257.610nm),Mo(202.032nm),P(178.222nm),Si(250.690nm),Ba(455.403nm);(4)The detection limit of this method is 6 X 10-4～7 X 10-2μg/mL.The recovery for standard addition was 95.7%～110%.and the relative standard deviation was 1%～7%.(5)This method was used to analyze NIST SRM 277(Tungsten Concentrate)and SRM 2430(Scheelite Ore),test results was in the expanded uncertainty of SRMs’s certified or reference value.One tungsten concentrate and one roasted molybdenum concentrate was prepared.The procedures were:election material,component design,blending,grinding,mixing,homogeneity test,stability test,value certification.The granularity of candidate material was under 74μm,and the homogeneity of each element was good.