Skip to main content

USE OF PHOSPHORIC ESTERS IN THE FLOTATION OF FINELY DIVIDED OXIDIZED ORES.

Objective

THERE IS CURRENTLY NO COLLECTOR OFFERING SATISFACTORY SELECTIVITY FOR THE RECOVERY OF ALL OF THE ORES CONTAINING RARE EARTHS IN A FINELY CRUSHED ORE, OR ONE THAT IS FINELY DIVIDED IN A NATURAL STATE (GRAIN SIZE LES THAN 40 OR 50 MICROM).

IN VIEW OF THE ENCOURAGING RESULTS OBTAINED BY BRGM ON ORES OF THIS TYPE, CERTAIN PHOSPHORIC ESTERS EMERGE AS THE MOST SELECTIVE COLLECTORS FOR FLOTATION IN THE FORM OF DEFLOCCULATED PULP.

THE ECONOMIC APPEAL OF THE PROPOSED RESEARCH IS TWOFOLD:
- TO PROMOTE NEW FLOTATION PROCESSES AND THE USE OF NEW COLLECTOR REAGENTS OF EUROPEAN ORIGIN;

- TO DIVERSIFY AND EXPAND THE SOURCES OF SUPPLY FOR THE EUROPEAN INDUSTRIES CONSUMING T.R., NB, TA CONCENTRATES BY PROMOTING THE WORKING OF NEW DEPOSITS OR UPGRADING THE BY PRODUCTS OF MINES ALREADY IN OPERATION. THIS APPLIES PARTICULARLY TO RARE-EARTH ORES IN AFRICA, AMERICA, OR TURKEY WHICH ARE REPUTED TO BE DIFFICULT TO ENRICH BY CONVENTIONAL FLOTATION, AND THE DEPOSITS OF WHICH HAVE BEEN ASSESSED BY A EUROPEAN COMPANY COUNTING AMONG THE MAIN WORLD PRODUCERS OF RARE-EARTH OXIDES.
Work has been conducted in order to:
develop new phosphoric ester (PE) derived flotation collectors with optimum performance for the concentration of finely divided oxidized rare earth element (REE) bearing ores;
define REE bearing minerals occurring in typical ores;
develop flotation techniques using PE derivatives, alone or in conjunction with other promoters, as collectors applicable to difficult to beneficiate REE ores.
This could promote the development of new deposits which would constitute new potential REE sources for European producers.

Laboratory investigations conducted on 3 REE ore samples, differing by the nature of the main REE bearing minerals, clearly show that certain types of phosphoric esters exhibit high affinity for yttrium and REE containing apatite as well as for monazite, and could be used as collectors for concentrating these minerals by flotation, provided that the composition of the gangue allows selectivity to be achieved. Results of flotation tests on the monazite ore indicate that monazite could be efficiently separated from stronianite, dolomite, baryte, siderite, iron oxides and manganese oxides, whereas concentration performance sharply drops in the presence of high proportions of manganese and iron containing dolomite which responds quite well to flotation with phosphoric esters. Removing most of this contaminant by tabling leads to a gravity preconcentrate which is refined by flotation to produce concentrates assaying 94% to 97% monazite. Results of flotation tests on the bastnaesite ore suggest that phosphoric esters have low affinity for bastnaesite.

Separation of yttrium and REE containing apatite from silicates and iron minerals by flotation with a phosphoric ester collector has led to marketable grade apatite concentrates with acceptable contents of residual magnesium oxide and REE oxides. This makes possible conversion of phosphoric oxide values to marketable wet process phosphoric acid as well as recovery of rare e arth elements and yttrium.

The most efficient phosphoric ester collectors for REE and yttrium containing apatite should have a high content of monoorthophosphoric ester, a low concentration of residual orthophosphoric acid and an appropriate number of ethylene oxide groups (n) giving satisfactory apatite recovery with moderate detrimental effect on the apatite content of the concentrates. Within the experimental range explored, the most effective phosphoric ester collectors for monazite are characterized by high n values, low concentrations of nonphosphated products and orthophosphoric acid, and high concentrations of monoorthophosphoric ester.

The objectives of the research were:
to develop new phosphoric ester (PE) for flotation collectors with optimum performance for concentrating finely divided oxidized rare earth elements bearing ores (REE);
to define REE bearing minerals occurring in typical ores;
to develop flotation processes using PE derivatives.

Investigations conducted on 3 REE ore samples differing by the nature of the main REE bearing minerals shown that certain types of phosphoric esters exhibit high affinity for yttrium and REE containing apatite as well as for monazite, and could be used as collectors for concentrating these minerals by flotation provided that the compositio of the gangue allows selectivity to be achieved. Results of flotation tests on the monazite ore indicate that monazite could be efficiently separated form strontlanite, baryte, iron and manganese oxides, whereas concentration performance drops in the presence of high proportions of manganese and iron containing dolomite which responds well to flotation with phosphoric esters. Removing most of this contaminant by tabling leads to a gravity preconcentrate which is refined by flotation to produce concentrates assaying 94 to 97% monazite. Results of flotation tests on the bastnaesite ore suggest that phophoric esters have low affinity for bastnaesite.

Separation of yttrium and REE containing apatite form silicates and iron minerals by flotation with a phosphoric ester collector has led to marketable grade apatite concentrates with acceptable contents of residual magnesium oxide and R2O3.

This makes possible conversion of phosphours pentoxide values into marketable wet process phosphoric acid besides recovery of REE and yttrium.

The best separation performance of REE containing apatite has been obtained with a PE collector including 70% monoester, 4 ethylene oxide groups per molecule, a linear hydrophobic chain and low amount of residual nonphosphated products.

Clear conclusions cannot be drawn regarding th e influence of the composite of PE on the selectivity of separation.
A) THE GERLAND COMPANY'S LABORATORY:

- SYNTHESIS AND PLOTTING OF CHARACTERISTICS OF THE NEW PHOSPHORIC-ESTER-BASED COLLECTORS.

B) THE BRGM WILL PURSUE THE FOLLOWING PROGRAMME:

1.- PLOTTING OF THE CHARACTERISTICS OF THE ORES TO BE STUDIED.
2.- MECHANICAL PREPARATION OF THE ORES GROUND TO RELEASE SIZE.
3.- PRELIMINARY ENRICHMENT TESTS FOR FLOTATION PURPOSES.
4.- ANALYSIS OF THE RESULTS OF THE PRELIMINARY TESTS.
5.- FURTHER FLOTATION TESTS WITH NEW REAGENTS PRODUCED BY GERLAND.
6.- TESTS TO OPTIMIZE FLOTATION PERFORMANCE.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Bureau de Recherches Géologiques et Minières (BRGM)
Address
39-43 Quai André Citroën
75739 Paris
France

Participants (2)

Gerland SA
France
Address
50 Cours De La République
69625 Villeurbanne
TECHNICAL UNIVERSITY OF MUNICH
Germany
Address
21,Alte Akademie 16
85350 Freising