The Application And Mechanism Of Sodium Polyacrylate In The Selective Flocculation Direct Flotation Of Fine Hematite

The reverse flotation process often was used further to improve the iron concentrate grade after magnetic separation,but for the reverse flotation of fine low-grade iron concentrate,there are disadvantages such as large reagent consumption,poor selectivity,and poor flotation effect.This thesis realizes the reuse of low-grade fine iron tailing resources by the magnetic separation-selective flocculation flotation process.The effect of sodium polyacrylate on the flotation of fine hematite and quartz was investigated for the fine hematite flocculation flotation process by using environmentally friendly sodium polyacrylate as a flocculant.The adsorption mechanism and morphology of sodium polyacrylate on the hematite surface were revealed by the FTIR,XPS,Zeta potential test,SEM,and EDS analysis,which improved the theoretical study of selective flocculation flotation of fine hematite.The main research conclusions are as follows:（1）The difference in molecular weight of sodium polyacrylate influences its structure and properties.The micro-flotation tests show that sodium polyacrylate have a differentiated effect on the flocculation flotation of fine hematite.The response surface and contour map fitting results of sodium polyacrylate molecular weight,dosage,and pulp p H on mineral flotation recovery showed that the molecular weight range of sodium polyacrylate is suitable for flocculation flotation of fine hematite was from 3×10⁶ to 1×10⁷（PAA-1,PAA-2,PAA-3）.The best effect of sodium polyacrylate on flocculation flotation of fine hematite was achieved when the molecular weight was from 4×10⁶ to 5×10⁶（PAA-1）.The relationship between molecular weight and dosage of sodium polyacrylate and recovery ratio was modeled mathematically in three dimensions using the Gauss function and Gaussian function,and the model fitting equations could be obtained.The optimal molecular weight and dosage conditions of sodium polyacrylate were screened according to the model fitting equation.（2）The flocculation flotation of fine hematite is affected by inevitable metal ions and flotation tests have shown that Fe³⁺has a facilitating effect on fine hematite flocculation flotation,which can expand the effective flotation p H range of fine hematite from 6.5～8 to 4.5～9.Ca²⁺,Mg²⁺,Zn²⁺,Pb²⁺,Cu²⁺,and Mn²⁺had an inhibitory effect on the flocculation flotation of the fine hematite.The artificially mixed ore experimental results showed that sodium polyacrylate has a good selective flocculation effect on the fine hematite,and can realize the separation flotation of fine hematite and quartz.The introduction of certain concentration of Fe³⁺can further improve the Fe recovery.（3）Based on the TOC test of PAA-1,PAA-2,and PAA-3 on the hematite surface and the fitting of the adsorption isotherm equation.The results indicated that the adsorption capacity of sodium polyacrylate on the hematite surface increased with molecular weight.The PAA-1,PAA-2,and PAA-3 were monolayer adsorption on the hematite surface according to the change of initial concentration.（4）The interaction between the fine hematite and quartz particles in medium water was investigated based on sedimentation and floc size tests and DLVO and EDLVO calculations.The results show that non-selective agglomeration between fine hematite and quartz particles was easily generated without sodium polyacrylate.When the sodium polyacrylate was added,the interaction force between the fine hematite and quartz particles was repulsive.Sodium polyacrylate could eliminate the non-selective agglomeration between the fine hematite and quartz particles.（5）The adsorption mechanism of sodium polyacrylate on the hematite surface was studied.The change of Zeta potential on the surface of hematite and the results of infrared spectrum analysis showed that sodium polyacrylate adsorbed on the hematite surface by chemisorption.The interaction between Fe³⁺on the hematite surface and the active group-COO^-in sodium polyacrylate was determined.The dimer was formed by the XPS analysis and test,including two forms of（RCOO）₂^2-or RCOOH-RCOO^-.Sodium polyacrylate is adsorbed in trace amounts on the quartz surface mainly by hydrogen bonding.The SEM and EDS tests found sodium polyacrylate showed flocculent point adsorption on the hematite surface.（6）The magnetic separation-selective flocculation flotation process was used to recover the low-grade strong magnetic separation tailings.The 1.5 kg/t of sodium hexametaphosphate was added to the roughing process.The magnetic separation was carried out at the magnetic field strength of 1.9 T for roughing and sweeping and 1.5 T for selecting.The obtained magnetic separation concentrate was one rougher-one concentration flocculation flotation process with sodium hexametaphosphate 400 g/t,PAA-1+PAA-3 300g/t+100 g/t,and sodium oleate 1000 g/t under natural p H conditions,finally obtained a Fe concentrate with 53.41%Fe grade and 68.17%recovery from flotation operation.The concentrate Fe grade and recovery increased by 5.03percentage points and 22.18 percentage points,respectively,compared to the no-flocculant condition.78 Figures,33 tables,215 references...