Avaliação de sistemas de drenagem com geossintéticos para diminuição da umidade no minério de ferro da Serra de Carajás

Abstract

The iron ore produced in the Serra dos Carajás/PA, the largest reserves of iron ore in the world, has high moisture when compared with iron ore extracted and processed in other countries. Due to high rainfall in the state of Pará, the moisture content of the ore remains high during transportation and storage. This fact is causing additional costs, making the product more expensive since the retained water does not add value to the commercial product. This paper presents results of tests performed in the laboratory to evaluate the reduction of moisture content of iron ore "sinter feed" (SFCJ) extracted by the Company VALE SA in Carajás, PA, when geosynthetic drainage systems are used. Gradient Ratio (GR) tests were performed to evaluate the drainage conditions of synthetic materials in different stages of loading and hydraulic gradients. Special tests were performed on the same equipment for the evaluation of the moisture reduction in the iron ore, which consisted of applying vacuum using a pump at the bottom of the specimen. The results presented show that the use of geosynthetics combined with a vacuum of approximately 100 kPa reduced the moisture content of iron ore at 40% of initial moisture content of the specimen. Studies to evaluate the abrasive wear of synthetic materials in contact with the iron ore were also performed, simulating the condition that the ore will subjected in the wagons. In addition, drying column tests and lysimeter were conducted instrumented with tensiometers, moisture meters and temperature gauges to monitor the drying process of iron ore. With the results of a numerical simulation was performed using the software VADOSE / W (GEOSTUDIO International Ltda.), Varying the conditions of drainage or drainage systems in order to evaluate the efficiency in the process of moisture reduction of iron ore, both during transport and storage.