Process and system for dry recovery of fine and superfine grained particles of oxidized iron ore and a magnetic separation unit
The present invention refers to a system and method for the totally dry treatment of iron-ore wastes from previous mining operations, suitable for both the processing of ore wastes deposited in barrages and wastes stored in piles. The present invention solves the problems of magnetic separation processes that employ the wet and waste-dewatering way, eliminating the risks which throwing solid wastes into retention barrages bring by a system and method wherein the moisture degree of the ore is reduced by means of a mechanical stir dryer (using natural gas to prevent contamination), which is then sorted into various factions and finally separated magnetically, with the important difference of being an entirely dry process.
1. A system for dry recovery of fine and superfine particles of oxidized iron ore, wherein the recovery is carried out in a totally dry metallurgical route, the system comprising:
a drying means with mechanical stirring,
at least one set of cyclones arranged in series for air-sorting of fed material at different granulometric ranges; and magnetic separation using permanent high intensity rare earth roll separators capable of reaching up to 13,000 gauss arranged at a conveyor belt with an inclination that actuates over the inertial reference of non-magnetic fine-rained particles of oxidized iron-ore and prevents their dragging with a magnetic fraction and contamination of a oxidized iron ore concentrate.
2. A system according to claim 1 , wherein the metallurgical route further comprises a complementary systems for material feed, preliminary reduction of ores, transport, storage, sieve sorting, sleeve filters.
3. A system according to claim 1 , wherein stacks are provided for stocking oxidized iron-ore.
4. A process for dry recovery of fines and superfines of oxidized iron ore, comprising the steps of:
(a) drying and disaggregating the ore by mechanical stirring;
(b) selective air-sorting on the basis of the granulometry of the material in a serial cycloning operation; and
(c) magnetically separating by means of permanent high intensity rare earth roll separators operating with a magnetic intensity that can reach up to 13,000 gauss and arranged at a conveyor belt with an inclination that actuates over an inertial reference of non-magnetic fines of oxidized iron ore and prevents their dragging with a magnetic fraction and contamination of the oxidized iron ore concentrate.
5. A process according to claim 4 , further comprising a step of transferring the ore to a storage area for drying or disaggregation by a conveyor belt through a duct provided with a shaking feeder.
6. A system according to claim 1 wherein the permanent high intensity rare earth roll separators each comprise magnets of north polarity with an intermediate gap, followed by magnets of south polarity with an intermediate gap, with a magnet-thickness:gap-thickness ratio of 3:1.