MINERAL ORE FLOTATION AID

FIELD OF THE INVENTION

The present invention is related to mineral ore processing, particularly low-grade ore processing. The present process comprises froth flotation to recover ore and the reagents used during said process.

BACKGROUND OF THE INVENTION

Mineral ores such as metallic ore are obtained from deposits referred to as either high or low-grade deposits. One process that is used to recover and concentrate minerals obtained from ores is froth flotation. With the steady depletion of high grade, easy to process ores, the exploitation of low grade, more complex and disseminated ore reserves has become necessary. Because of this, more sophisticated and innovative separation technologies for concentrating valuable minerals are required. In terms of flotation, the development of more selective collectors and reagents is critical to its success in treating these low grade, difficult to process ores.

In a froth flotation process, the ore is subject to comminution, such as by wet grinding, to reduce particle size of the mineral ore. Additives, such as collectors, frothers, dispersants, surfactants and activators, are added to the ground ore, or pulp, to assist in separating valuable minerals from undesirable gangue portions of the ore in subsequent flotation steps. The pulp is then aerated to produce a froth at the surface. The materials that adhere to the bubbles or froth are collected as concentrates. Selective suppressants or depressants inhibit the adhesion of the certain minerals to the bubbles or froth, thus assisting in the separation of the froth products from the minerals in the pulp.

Selectivity in froth flotation is controlled by the selective adsorption of reagents on minerals at the mineral/water interface. Reagents that impart sufficient hydrophobic character to minerals on adsorption, such that they are rendered floatable, are referred to as collectors. In general, the commercial collectors currently used include sulfydryl

collector agents such as xanthate, and fatty acid based collector agents such as sodium oleate.

US patent no. 4,699,711 discloses a process for the flotation of sulfide minerals using preferably short-chain alkyl-substituted thionocarbamates, while US patent no. 5,307,938 teaches the use of polyacrylate polymers, homopolymers and copolymers as a dispersant for iron ore pulps to significantly increase the recovery of iron oxide in deslime, flotation or other separation processes requiring a highly dispersed pulp. A selective separation of ore values is taught in US patent no. 6,536,595, which comprises the use of a water-soluble, organophophonate treatment reagent, preferably combined with a polymeric dispersant.

Accordingly, a need remains for more effective and efficient means for the selective separation of ore values from ground mineral ore containing gangue material. Particularly in view of the increasing requirements of the use of low-grade ores.

SUMMARY OF THE INVENTION

A method is provided for the selective separation of ore values when a ground mineral ore containing gangue material is first dispersed in an aqueous medium and thereafter conditioned with an effective amount of a treatment reagent whereby the recovery of valuable minerals from a froth flotation process is increased. In an embodiment of the present invention, the treatment reagent is a water-soluble ethylene oxide/propylene oxide copolymer.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and benefits obtained by its uses, reference is made to the accompanying drawings and descriptive matter. The drawings are not intended as showing the limits of all of the ways the invention can be made and used. Changes to and substitutions of the various components of the invention can of course be made. The invention resides as well in sub-combinations and sub-systems of the elements described, and in methods of using them.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a graph depicting the effect of the varying doses of the reagent on polymetallic recovery in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity).

"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, or that the subsequently identified material may or may not be present, and that the description includes instances where the event or circumstance occurs or where the material is present, and instances where the event or circumstance does not occur or the material is not present.

A method is provided for the selective separation of ore values when a ground mineral ore containing gangue material is first dispersed in an aqueous medium and thereafter conditioned with an effective amount of a treatment reagent whereby the recovery of valuable minerals from a froth flotation process is increased. In an embodiment of the present invention, the treatment reagent is a water-soluble ethylene oxide/propylene oxide copolymer.

The present process provides a means for improving the separation of mineral values from their associated gangue. The present invention will be described with respect to flotation recovery of metal values from polymetalic ores. However, this method may also be compatible with other ore recovery systems, wherein mineral values are selectively separated from their associated gangue. The method or process comprises the addition of an effective amount of the reagent to the froth flotation process that enhances the ore recovery. The particular amount that is effective will vary depending

upon variables, such as but not limited to the particular ore processed and the specific composition of the reagent.

In an embodiment of the invention, the treatment reagent comprises a water-soluble ethylene oxide/propylene oxide copolymer. The copolymer can be of varying forms, and this reagent, when added to the flotation feed slurry enhances the recovery of valuable minerals and/or polymetallics therefrom, which includes but is not limited to copper, iron and nickel.

As used herein, the term "EO/PO" is synonymous with the oxyalkylene group and serves as a convenient short hand to designate polyoxyalkylene groups, (ethylene oxide/propylene oxide copolymers). The copolymers are comprised of polyoxyethlene polyoxypropylene polymers, with varying percentages by weight of ethylene oxide. In one embodiment, the copolymer is created by the controlled addition of propylene oxide to two hydroxyl groups of propylene glycol. Ethylene oxide is then added to sandwich the hydrophobe between hydrophilic groups. Suitable polymeric reagents within the scope of the present invention comprise copolymers having the structure

EO-PO-EO

In an alternate embodiment, the hydrophobic and hydrophilic positions are reversed, such that the hydrophilic group is sandwiched between the hydrophobic groups, as for example

PO-EO-PO

In a further alternate embodiment, the copolymer may be derived from the sequential addition of propylene oxide and ethylene oxide to ethylene-diamine. An example of the same may have the structure

E0 )JJ ^ ^>> 00o s PO-EO

EO-PO PO-EO

In a further embodiment, the copolymer may also be may be derived from the sequential addition of propylene oxide and ethylene oxide to ethylene-diamine, but the hydrophobic and hydrophilic blocks are reversed, to create a structure

PO^EO -EO-PO

PO-EO EO-PO

The backbone in either of the above two embodiments can vary. Examples of the same, but not meant to be limiting in any way, include erythritol

pentaerythritol

A further example of a backbone for the branched embodiments is N-CH ₂ - CH ₂ -N.

The reagent may also be formed from various combinations of the embodiments of the copolymer. In any of the embodiments, the amount of EO present in the copolymer is from about 10 to about 90 percent by weight, with one embodiment being from about 20 to about 80% by weight. Additionally, the amount of PO present

in the copolymer is from about 90 to about 10% by weight, with an embodiment of from about 80 to about 20% by weight. Examples of the copolymers include by are not limited to Pluronic®L61 and Pluronic®F108 (BASF corporation, Mount Olive, New Jersey, USA).

The number average molecular weight of the water-soluble copolymers of the present invention fall within the range of from about from about 1,000 to about 500,00, with an embodiment in the range of about 2,000 to about 20,000.

The method or process comprises the addition of an effective amount of the reagent to the froth flotation process which enhances the ore recovery, with the particular amount that is effective changing depending upon variables, such as but not limited to the particular ore processed and the specific composition of the reagent. The reagent may be added in an amount of from about 0.01 grams/ton dry solids to about 50.0grams/ton dry solids, with an embodiment comprising from about 0.1 to about to about 15.0 grams/dry ton.

The method may be carried out at varying pH levels, which may be dictated by the conditions at the time of the froth flotation. However, the pH range for the present process is from about 5 to about 9, with an embodiment of about neutral pH in many instances.

The recovery value is the percentage of valuable metals obtained by the ore. With low-grade ore, it is not unusual to have a recovery of 80%, thereby leaving 20% of the valuable metal behind. By using the presently disclosed reagent in the process, such as by froth flotation, the recovery value can be increased, resulting in an increase of revenue from the ore. When the EO/PO copolymer described herein comprises the reagent, the recovery values from the addition of the reagent increase from about to 2 to about 10%, to total recovery levels of from about 50 % to about 99.0%, with one embodiment showing an increase in recovery of from about 3 to about 8%, to result in a total recovery of from about 75.0 to about 95.0%.

Example

Table 1

2007 MINERAL PROCESSING RESULTS - MONTHLY AVERAGES

Metal 1 Metal 2

Date Feed Cone tail % Recovery Feed Cone tail % Recovery

1/7/07 0.455 5.51 82.6 0.261 3.47 86.5

2/1/07 0.424 5.53 80.4 0.231 3.26 85.7

3/1/07 0.55 5.71 84.5 0.31 3.59 88.6

4/7/07 0.49 5.44 83.3 0.28 3.62 88.7

5/7/07 0.571 5.57 84.8 0.36 3.36 88.9

6/7/07 0.585 5.82 86.7 0.334 3.62 88.6

7/7/07 0.42 5.7 80.7 0.249 3.45 88.8

8/7/07 0.525 5.35 87.5 0.343 3.66 93.5

9/7/07 0.68 5.79 89.8 0.36 3.41 93.2

10/7/07 0.431 5.599 83.6 0.273 3.726 89.5

11/7/07 0.424 5.62 83.6 0.255 3.54 87

12/7/07 0.46 5.606 82.7 0.289 3.15 83.8

2007 AVG 0.50 5.60 0.00 84.18 0.30 3.49 0.00 88.57

Table 1 shows the monthly average plant metal recoveries without any reagent addition and is used as baseline for the reagent addition test work to show the increase in metal recoveries. Reagent was added into the mill feed at the levels shown. The feed units are percent by dry weight and the reagent addition was added as grams of reagent per ton of dry ore. The reagent in this case was of the EO-PO-EO form.

Table 2 shows the average metal recoveries at different reagent dosage rates.

Table 2

REAGENT ADDITION PLANT TRIAL RESULTS

Reagent Nickel Copper

% Metal

%Metal 1 2 g/τ Feed Cone tail Recovery Feed Cone tail Recovery

0 0.50 5.60 0.00 84.18 0.30 3.49 0.00 88.57

1.0 0.37 4.48 0.07 81.68 0.27 2.63 0.02 94.24

2.5 0.56 5.60 0.08 87.49 0.40 2.97 0.02 95.24

5.0 0.53 5.06 0.08 86.46 0.34 2.71 0.02 93.90

The increase in metal recoveries at different reagent dosage levels is also demonstrated in graphic form in Fig.1.

While the present invention has been described with references to preferred embodiments, various changes or substitutions may be made on these embodiments by those ordinarily skilled in the art pertinent to the present invention with out departing from the technical scope of the present invention. Therefore, the technical scope of the present invention encompasses not only those embodiments described above, but all that fall within the scope of the appended claims.