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Two great concerns related to long distance slurry pumping systems are plug formation and sediment compaction. These problems are avoided in the Samarco Pipeline by adding lime. However, the presence of calcium ions in the process represents production losses, so alternative reagents were tested. Two organic coagulants and two flocculants were evaluated at dosages of 5, 100 and 300 ppm by performing rheology, settling, penetration and angle of repose tests, before and after 24 hours under agitation. It was verified that a dosage of 300 ppm of the organic coagulants affected the slurry properties likewise lime, so that they can replace it under this condition. Lower dosages do not result in coagulation or do not maintain the slurry coagulated with agitation, therefore they are considered insufficient. The changes generated by the flocculants in the slurry characteristics are not satisfactory since they do not minimize the high probability of plug formation. It is concluded that the aggregation state of the iron ore slurry must be changed by the coagulation mechanism in order to operate the system efficiently and safely. [ABSTRACT FROM AUTHOR]