Chapter 17 - INDUSTRIALLY USEFUL PROPERTIES OF SOUTH

FLORES, HORACIO RICARDO; E MATTENELLA, LILIAN; VALDEZ, SILVANA

Handbook on Borates: Chemistry, Production and

NOVA SCIENCE PUBLISHERS INC

Año: 2010; p. 431 - 439

Since most of the borates produced in South America (concentrates and processed products) are exported and the technical marketing regulations have become more strict, producers have to improve competitiveness through technology, including some concentration and/or purification stage in the mill circuit. The objective of the separation is a graded product in B2O3 and lowered in undesirable impurities (mainly iron, arsenic, chlorides and sulphates). Concentration steps usually involved in the borate processing are gravity separation, froth flotation, magnetic separation and size classification, based on the differences of specific weight, superficial energy, magnetic susceptibility and hardness, respectively. Another easy grading method is calcination; that is the conversion to a less hydrated crystalline form. Unfortunately, impurities are also graded, thus the raw material must be concentrated before or after the calcination step or purified. This paper reports the results obtained of the above mentioned properties for the industrial interesting South American borates (colemanite, hydroboracite, ulexite and tincal), and the techniques employed to collect pure samples.