Flotation Theory Of Bastnaesite Type Rare Earth Ore

Rare earth is an important strategic resource in the world,and has great strategic significance for the development of national defense,aerospace and other fields.Bastnaesite type rare earth ore is a typical representative and an important source of light rare earth minerals,the flotation separation of bastnaesite is the key to develop and utilize this type rare earth ore.This paper takes bastnaesite,calcite and fluorite as research objects,and has researched the lack of surfacel properties of bastnaesite and gangue mineral,the adsorption mechanism of flotation agents and mineral surface,and the floatability effect of metal on minerals.The main research conclusions are as follows:The surface of bastnaesite was rich in Ce,La and Nd rare earth elements,and the content of Ca element on the surface of calcite and fluorite is high.With the increase of pH,the concentrations of Ce?OH?₂⁺and Ce?OH?²⁺in the solution gradually rise,which are the main active sites The PZC of three minerals in ultrapure water were 8.4,7.8 and 9.8,respectively.The PZC of fluorite was the biggest when pH was 7,this was advantageous for the collector electrostatic adsorptionWhen salicylic acid and H205 were used as collectors,bastnaesite had good floatability,fluorite had a little floatability,but calcite could not float.When the pulp pH was 8-9,the floatability difference between bastnaesite and gangue minerals is the largest.The oxime anion complexed with RE?OH?²⁺and RE?OH?₂⁺active sites of hydrolyzed rare earth ions on bastnaesite surface,formed the stable five-membered ring chelate,and increased the hydrophobicity of bastnaesite surface.At this time,the surface of fluorite was positively charged,and the oxime anion was adsorbed on the mineral surface by electrostatic action.The selective depression effect of sodium silicate and oxalic acid on calcite and fluorite was obvious,and the depression effect of sodium silicate on calcium-bearing gangue was derived from:silicate colloidal Si?OH?₄ was adsorbed on the mineral surface,the SiO?OH?₃^-of sodium silicate hydrolysis localization adsorded on the gangue mineral surface and formed calcium silicate precipitation.When the pulp pH was 8 and salicyllic acid concentration was 4×10^-4 mol/L,the flotation concentrate with the REO grade of 19.39%and the recovery of 60.87%was obtained from the artificially mixed ore with the REO grade of 7.61%.When the pulp pH was 9 and H205 concentration was 4×10^-4 mol/L,the flotation concentrate with the REO grade of 13.26%and the recovery of 63.90%was obtained from the artificially mixed ore with the REO grade of 7.61%.When the pulp pH was 8-9,H205 concentration was 4×10^-4mol/L and sodium silicate concentration was 20 mg/L,the flotation concentrate with the REO grade of15.50%and the recovery of 56.83%was obtained from the artificially mixed ore with the REO grade of7.61%.The minerals floatability effect of metal ions showed that Pb²⁺and Fe³⁺produced different effects for three minerals flotation using H205 as collector when the pulp pH was 8-9.For lead ions,the Pb?OH?⁺of hydrolysed lead ions formed RE-O-Pb⁺complex,and another part of Pb?OH?⁺electrostatically adsorbed on the mineral surface which increased the adsorption sites when Pb²⁺concentration was lower than5×10^-4 mol/L.However,the remaining lead ions in the solution complexed preferential with collector,this decreased the floatability of minerals.For iron ions,within the test rangehe,the Fe?OH?_3?s?of hydrolysed iron ions formed RE-O-Fe-OH complex,which reduced the density of active sites;the remaining iron ions in the solution consumed the collector and reduced the recovery of minerals by reducing the effective concentration of collector.