Resende, Tulio Viegas BicalhoLuz, José Aurélio Medeiros da2018-09-262018-09-262018RESENDE, T. V. B.; LUZ, J. A. M. da. Error variance of short duration sieving. REM - International Engineering Journal, Ouro Preto, v. 71, n. 2, p. 305-311, abr./jun. 2018. Disponível em: <http://www.scielo.br/scielo.php?pid=S2448-167X2018000200305&script=sci_arttext>. Acesso em: 03 mai. 2018.18070353http://www.repositorio.ufop.br/handle/123456789/10259n this study, the variance of ordinary sieving test error was determined concerning the specification limit of sized iron ore product by subtracting the fundamental error (described by the Gy's formalism for sampling), from the global error (recoverable from database of historical values). The results allowed the calculation of the confidence interval for the percentage of material finer than the upper screen specification limit. Thereafter, a method to estimate the so-called effectiveness coefficient of the screening operation was developed, which is the ratio between number of particle presentations to passage and the number of oscillations during the material shaking on the screen surface. This estimation was based on the probability statements and particle size distribution of the feed. Considering the size distribution of the products tested in this study, the results have shown that the sieving time could be reduced when determining the percentage of material finer than the upper specification mesh.en-USabertoScreeningGy's formalismIron oreSampling theorArtigo publicado em periodicoA REM - International Engineering Journal - autoriza o depósito de cópia de artigos dos professores e alunos da UFOP no Repositório Institucional da UFOP. Licença concedida mediante preenchimento de formulário online em: 12 set. 2013.