Study On The Separation Properties Of Weakly-magnetic Iron Mineral Intergrowths

So-called refractory iron ores are presently characterized by low iron grade, close intergrowth of many components and fine-dissemination of valuable minerals. In the separation of finely-disseminated or micro-disseminated iron ores, there exist a large number of intergrowths which will enter into middlings and need further separation, or enter into concentrate and resultantly reduce the grade, or enter into tailings and result in the loss of useful components. So it is helpful to optimize the separation by studying the properties of intergrowths.The separation properties related to gravity separation, magnetic separation and flotation of the weakly-magnetic iron ore intergrowths with the valuable mineral intergrowth degree of1%、10%、16%、35%、57%、84%、98%were studied quantitatively and the mechanism of reagent action were studied by means of adsorption tests, contact angle tests and so on.The effect of density, specific susceptibility and other physical properties of intergrowths on the separation were studied, and the results showed that the density increased gradually with the increment of intergrowth degree. The intergrowths showed nearly non-magnetism when the degree was less than10%, weak magnetism when the degree was10%-35%, and middle magnetism when the degree was more than35%. By gravity separation, it is easily to separate the two intergrowths with their degree difference of more than55%and to discard the intergrowths with the degree of less than16%, and the concentrate with the degree of over57%can also be obtained, while it is difficult to separate the intergrowths with their degree difference of less than35%. In the magnetic separation, as the intergrowth degree decreased, the magnetic field intensity required to recover intergrowth increased, and the specific magnetic force reduced. Moreover, the intergrowths with the degree of less than10%were difficult to be recovered by magnetic separation.The effect of collectors, activators and depressants on the flotation behavior of the intergrowths in anionic and cationic systems was studied respectively. In cationic reverse flotation system, lauryl amine showed a strong collecting capability for different intergrowths in terms of the recovery, which indicated that the selectivity of lauryl amine was poor. In anionic reverse flotation system, the pulp should be under strong alkaline (at pH11.5) condition, with the increase of intergowth degree, the the recovery was decresed first fast and then slowly, the truning point appeared in the degree range of16%-35%.The starch had inhibitory effect to different intergrowths, and the inhibition in anionic reverse flotation was stronger than that in cationic reverse flotation. The higher the intergowth degree was, the more sensitive the inhibition of starch was, especially for the intergrowth degree of over16%.The adsorption tests showed that both lauryl amine and starch were adsorbed on the surface of the intergrowths. As the intergrowth degree increased, the adsorption first increased rapidly, when the intergrowth degree was above16%, the increase began to slow down, which showed that starch was able to effectively inhibit the iron ore intergrowths with the intergrowth degree of above16%and contribute to the reverse flotation separation.The contact angle test results showed that the contact angle between the intergrowth and pure water increased with the increment of the intergrowth degree. After the adsorption of lauryl amine or sodium oleate, the contact angle of all intergrowths increased, and the contact angle decreased with the increment of the intergrowth degree. After the adsorption of starch, the contact angle of all intergrowths reduced, and the decrease increased with the increase of the intergrowth degree, and therefore the inhibition was more sensitive to the intergrowth with high degrees.