Por: Francisco J. Sotillo, PerUsa EnviroMet, Inc. y Marten Walters, KEMWorks Technology, Inc.

Abstract

The Bayóvar phosphate deposit in Sechura, Piura, Peru, has been known since the 1960s and as Direct Application Phosphate Rock (DAPR) since the 1970s. However, its direct application rock characteristics were studied mostly based on chemical characterization and solubility studies, with little emphasis on physical and mineralogical characterization studies.

In general, phosphate rock from Sechura has been used as raw material for the production of phosphoric acid and fertilizer derivatives such as TSP, DAP and MAP, and if a cluster with a smelter and sulfide refinery is established, the production of SSP due to the accessibility of sulfuric acid. Sechura is a rock that presents filtration problems that can limit the production capacity of phosphoric acid plants. 

This paper proposes that a complete characterization of the washed or beneficiated phosphate product from Sechura should be carried out in order to determine certain characteristics that will allow a better utilization of the phosphate rock. For example, the use of particle size related to its mineralogy, chemical composition and solubility, in order to obtain the optimum yield as a direct application phosphate rock and the optimum fraction for the production of phosphoric acid. 

The performance of the phosphate rock could be tested in a continuously operating pilot plant system. Thus, these systematic studies would lead to the production of a natural fertilizer and therefore marketed with much higher added value, the remnant of the improved phosphate rock being marketed for the production of phosphoric acid.

Under this approach, the mining producer obtains greater economic benefit for their products and the agricultural industry, both for crops and for livestock pasture improvement, DAPR, which is a natural, chemical-free product (more environmentally friendly) and more efficient due to its relatively slow dissolution compared to soluble fertilizers such as TSP, DAP and MAP and SSP if sulfuric acid is accessible. 

For example, direct application phosphate rock from Sechura could provide 50% to 55% of its phosphate content in the first year, 80% to 85% in the second year, and up to 95% in the third year, requiring reapplication in the fourth year. In this way, mining contributes to agriculture by providing better products, reducing costs and improving efficiencies.