Process and system for dry recovery of fine-and superfine-grained particles of oxidized iron ore and a magnetic separation unit

Abstract

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 fractions and finally separated magnetically, with the important difference of being an entirely dry process.

What is claimed is: 
     
         1 . A magnetic separation unit suitable for the separation of determined fractions corresponding to fine and superfine particles of oxidized iron ore, the magnetic separation unit comprising:
 a permanent high intensity rare earth roll magnetic separator operating with magnetic intensity that can reach up to 13,000 gauss and arranged at 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 an iron oxide ore concentrate.   
     
     
         2 . The magnetic separation unit according to  claim 1 , wherein the permanent high intensity rare earth roll magnetic separator comprises 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 where the magnet-thickness is greater than the gap-thickness. 
     
     
         3 . The magnetic separation unit according to  claim 2 , wherein the magnet-thickness: gap-thickness ratio is 3:1. 
     
     
         4 . The magnetic separation unit according to  claim 2 , wherein the magnets of north polarity include at least two adjacent magnets of north polarity with the intermediate gap thereof disposed between the two adjacent magnets of north polarity, and the magnets of south polarity include at least two adjacent magnets of south polarity with the intermediate gap thereof disposed between the two adjacent magnets of south polarity. 
     
     
         5 . The magnetic separation unit according to  claim 1 , wherein the permanent high intensity rare earth roll magnetic separator comprises conjugated magnets having the same polarity with a gap therebetween that create magnetic field lines that alternate throughout the permanent high intensity rare earth roll magnetic separator. 
     
     
         6 . 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 plurality of 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-grained particles of oxidized iron-ore and prevents their dragging with a magnetic fraction and contamination of a oxidized iron ore concentrate. 
     
     
         7 . The system according to  claim 6 , wherein the permanent high intensity rare earth roll magnetic 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 where the magnet-thickness is greater than the gap-thickness. 
     
     
         8 . The system according to  claim 7 , wherein the magnet-thickness: gap-thickness ratio is 3:1. 
     
     
         9 . The system according to  claim 7 , wherein the magnets of north polarity include at least two adjacent magnets of north polarity with the intermediate gap thereof disposed between the two adjacent magnets of north polarity, and the magnets of south polarity include at least two adjacent magnets of south polarity with the intermediate gap thereof disposed between the two adjacent magnets of south polarity. 
     
     
         10 . The system according to  claim 6 , wherein each of the permanent high intensity rare earth roll magnetic separators comprise conjugated magnets having the same polarity with a gap therebetween that create magnetic field lines that alternate throughout the permanent high intensity rare earth roll magnetic separator. 
     
     
         11 . A process for dry recovery of fines and superfines of oxidized iron ore, comprising the step of:
 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.   
     
     
         12 . The process according to  claim 11 , wherein the permanent high intensity rare earth roll magnetic 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 where the magnet-thickness is greater than the gap-thickness. 
     
     
         13 . The process according to  claim 12 , wherein the magnet-thickness:
 gap-thickness ratio is 3:1.   
     
     
         14 . The process according to  claim 12 , wherein the magnets of north polarity include at least two adjacent magnets of north polarity with the intermediate gap thereof disposed between the two adjacent magnets of north polarity, and the magnets of south polarity include at least two adjacent magnets of south polarity with the intermediate gap thereof disposed between the two adjacent magnets of south polarity. 
     
     
         15 . The process according to  claim 11 , wherein each of the permanent high intensity rare earth roll magnetic separators comprise conjugated magnets having the same polarity with a gap therebetween that create magnetic field lines that alternate throughout the permanent high intensity rare earth roll magnetic separator.