Segregação no transporte de fertilizantes comercializados em embalagens "BiG Bag"

Abstract

The majority of mineral fertilizers used in Brazil are sold in the form of granules mixture in order to provide, lower storage and transportation costs, lower probability of hardening, easier handling and also to simplify its use. Despite the advantages mentioned, such mixtures, which might present two or three primary macronutrients, secondary macronutrients and micronutrients, must have these nutrients uniformly distributed, so that the distribution in the field is homogeneous. However, in this kind of mixture some problems of heterogeneity might occur due to the segregation of granules, which might result in segregation of nutrients that will produce irregular application. The segregation is worrying concerning the application of the fertilizer as well as the sampling by the inspector, once it might generate analysis result that does not match the product real composition. The volume of fertilizers in a Big Bag makes it impossible for the inspector to homogenize the product prior to sampling, as required by law, in the case of smaller packets, thus requiring its own sampling methodology. Therefore, with the aim of evaluating the segregation of fertilizers and determining a sampling methodology for the Big Bag packaging, a study was developed, based on two formulas 02-30-10 and 12-15-15 distributed into four Big Bags each. Three sampling at three different times were carried out. The first was performed soon after packaging, the second, after the Big Bags had been transported on a truck for 407 km and the last after 696 km, both on dirty road and on asphalt. A conic tip double tube steering steel probe, for the sampling of five distinct horizontal levels, five vertical, one in the middle and one in each corner of the packet as well as one diagonal, which went through granulometric and chemical analysis individually. One compound sample was produced by pushing the probe vertically at three distinct points, and later on adding to the four packets portions for analysis. The results of granulometric and chemical analysis , at several points of sampling carried out in the vertical, horizontal e diagonal as well as the compound, after packaging and transportation of the Big Bags, in both formulas studied, show that if a grain mixture fertilizer is produced with raw-material with granules of homogeneous size, within the variation of SGN ± 5%, it presents fewer segregation problems regardless the sampling points mentioned, according to what happened to the formula 12-15-15, and the use of certain raw-material with granules which are incompatible to the other components in the mixture, lead to condenation of the product both chemically and granulometrically, according to what happened to the formula 02-30-10. The compound sample method proved itself efficient despite failing the granulometric analysis of the formula 02-30-10 (after packaging and transportation for 696 km), due to greater amount, size and round format of the triple superphosphate granules (TSP).