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Applied mineralogy and mineral surface analysis

(a) high transmission, (b) unlimited mass range, (c) parallel detec-

tion (i.e. all masses are measured virtually simultaneously), (d) high

mass resolution, (e) static imaging as a result of the above, and (f)

the ease of charge compensation for insulators.

The unique advantages of SIMS over other techniques are: (a)

high sensitivity (generally more sensitive than XPS), (b) molecular

composition of surface species (not just elemental composition)

which facilitates an unambiguous identification of the surface species,

(d) shallow depth of penetration (as small as one monolayer) which

is of direct relevance to flotation, (e) ability to detect both inorganic

and organic species, (f) depth profile, and (g) high resolution (with

the use of micro-focusing liquid metal ion guns, SIMS images

with submicron resolution may be obtained). The disadvantages of

SIMS are, (a) difficulty in quantifying surface species, (b) large

differences in sensitivities for different surface species, and

Much of the pioneering work on the use of SIMS in flotation sys-

tems was conducted in Cytec's Research Laboratory. SIMS and XPS

have been used in a variety of flotation systems, including plant and

laboratory flotation products and pure minerals. These studies have

been successful in detecting, identifying and mapping collector

species on mineral surfaces, as well as in investigating metal ion

activation of sulfide and gangue minerals in order to either explain

or solve plant related problems.

LLaasseerr IIoonn MMaassss SSppeeccttrroossccooppyy ((LLIIMMSS))

is a variation of SIMS and

uses two laser sources, such as Nd-YAG. The first laser, called the

ablation laser, hits the sample at a 90° angle and removes (or ablate)

material from the surface layers. The second laser is perpendicular

to the first laser (or parallel to the sample) and is positioned about

600 microns above the sample surface. The second laser is also

coupled with the first laser with delay times in the range of 700-1400

nanoseconds. The function of the second laser is to ionize the

ablated neutral material from the sample surface. The ions are then

focused using an electrostatic lens and analyzed by mass/charge

ratio using a time-of-flight drift tube. The major advantages of LIMS

are small analysis area (spot size typically in the range of 5-10

microns) and rapid analysis times (of the order of minutes).

The main disadvantage is greater sampling depths (of the order

500-1000 Å) in LIMS (it is 1-3 monolayers in SIMS). Other differ-

ences between LIMS and SIMS are, (a) spatial resolution is 1-3 microns

in LIMS (it is 1500 Å in SIMS), (b) imaging is not possible in LIMS

and (c) organic species and polymers cannot be analyzed by LIMS.

Mining Chemicals Handbook

3.3 Bibliography and references

References

1. Brinen. J. S. and Nagaraj, D. R., "Direct Observation of a Pb-

dithiophosphinate Complex on Galena Mineral Surfaces Using

SIMS", Surface and Interface Analysis, Vol. 21, 874-876, 1994.

2. Brinen, J. S. and Reich, F., "Static SIMS Imaging of the

Adsorption of Diisobutyl Dithiophosphinate on Galena

Surfaces", Surface and Interface Analysis, Vol. 18, 448-452, 1992.

3. Cameron, E.N., Ore Microscopy, Wiley, New York, 1961.

4. Chryssoulis, S., Stowe, K., Niehuis, E., Cramer, H. C., Bendel, C.

and Kim, J., "Detection of Collectors on Mineral Grains by

Tof-SIMS", Trans. Inst. Min. Metall., Vol. 404, C141-C150, 1995.

5. Craig, J.R. and Vaughan, D. J., Ore Microscopy and Ore Petrology,

Wiley, New York, 1994.

6. Gaines, R.V., Skinner, H. C. W., Foord, E. E., Mason, B. and

Rosenzweig, A., Dana’s New Mineralogy: The System of Mineralogy of

James Dwight Dana and Edward Salisbury Dana, 8th Edition, Wiley,

New York, 1997.

7. Kerr, P. F., Optical Mineralogy 4th Ed., McGraw, 1977.

8. Miller, P. R., Reid, A. F. and Zuiderwyk, M. A., "QEM*SEM Image

Analysis in the Determination of Modal Assays, Mineral

Association and Mineral Liberation", Proc. XIV Int. Mineral

Processing Cong., 8-3, Toronto, 1982.

9. Nagaraj, D.R. and Brinen, J. S., “SIMS Study Of Adsorption Of

Collectors On Pyrite”, SME Annual Meeting, Denver, CO,

Preprint #97-171, published in Int. J. Miner. Process., June 2001.

10. Nagaraj, D.R. and Brinen, J. S., “SIMS Study Of Adsorbed

Collector Species On Mineral Surfaces: Surface Metal

Complexes”, SME Annual Meeting, Phoenix, 1996,

Preprint #96-181.

Applied mineralogy and mineral surface analysis

11. "SIMS Studies of Mineral Surface Analysis: Recent Studies",

Trans. Ind. Inst. Metals, Vol. 50, No. 5, pp. 365-376, Oct. 1997.

12. Nagaraj, D. R. and Brinen, J.S., “SIMS Study Of Metal Ion

Activation In Gangue Flotation”, Proc. XIX Intl. Miner. Process.

Congress, SME, Chapter 43, pp. 253-257, 1995.

13. Nagaraj, D.R. and Brinen, J. S., “SIMS And XPS Study Of The

Adsorption Of Sulfide Collectors On Pyroxene”, Colloids and

Surfaces, Vol. 116, pp. 241-249, 1996.

14. Farinato, R. S. and Nagaraj, D. R., Larkin, P., Lucas, J., and

Brinen, J. S., “Spectroscopic, Flotation and Wettability Studies of

Alkyl and Allyl Thionocarbamates”, SME-AIME Annual Meeting,

Reno, NV, Preprint 93-168, Feb. 1993.

15. Brinen, J. S., Greenhouse, S. Nagaraj, D. R. and Lee, J., “SIMS

and SIMS Imaging Studies Of Dialkyl Dithiophosphinate

Adsorption On Lead Sulfide”, Int. J. Miner. Process. Vol. 38,

pp. 93-109, 1993.

16. Nagaraj, D.R., Brinen, J. S., Farinato, R.S. and Lee, J. S.,

“Electrochemical and Spectroscopic Studies of the Interactions

between Monothiophosphates and Noble Metals”, 8th Intl.

Symp. Surfactants in Solution, Univ. Florida, 1990; Pub. in

Langmuir, Vol. 8, No. 8, pp. 1943-49, 1992.

17. Nesse, W. D., Introduction to Optical Mineralogy, Oxford University

Press, New York, 1986.

18. Randohr, P., The Ore Minerals and Their Intergrowths, 2 vol., 2nd

Ed., Pergamon, New York, 1981.

19. Reid, A.F., Gottlieb, P., MacDonald, K. J. and Miller, P. R.,

"QEM*SEM Image Analysis of Ore Minerals: Volume Fraction,

Liberation and Observational Variances", Applied Mineralogy,

pp. 191-204, AIME, New York, 1984.

20. Uytenbogaart, W. and Burke, E. A. J., Tables for the Microscopical

Identification of Ore Minerals, Dover Publications, New York, 1985

Reprint.

Mining Chemicals Handbook

References for Tables

1. Anthony, J. W., Bideaux, R. A., Bladh, K. W. and Nichols, M. C.,

Handbook of Mineralogy, Volume I, Mineral Data Publishing,

Tucson, 1990.

2. Anthony, J. W., Bideaux, R. A., Bladh, K.W. and Nichols, M. C.,

Handbook of Mineralogy, Volume II, Parts 1 and 2, Mineral Data

Publishing, Tucson, 1995.

3. Anthony, J. W., Bideaux, R. A., Bladh, K.W. and Nichols, M. C.,

Handbook of Mineralogy, Volume III, Mineral Data Publishing,

Tucson, 1997.

4. Deer, Howie and Zussman, An Introduction to the Rock-Forming

Minerals, Longman, London, 1966.

5. Fleischer, M. and Mandarino, J. A., Glossary of Mineral Species

1991, The Mineralogical Record, Inc., Tucson, 1991.

6. Ford, W. E., Dana’s Textbook of Mineralogy, 4th Ed., Wiley, New

York, 1932.

7. Hurlburt, Jr., C. S. and Klein, C., Dana’s Manual of Mineralogy,

18th Ed., Wiley, New York, 1971.

8. Mandarino, J. A., Fleischer’s Glossary of Mineral Species 1999, The

Mineralogical Record, Inc., Tucson, 1999.

10. Palache, Berman and Frondel, Dana’s System of Mineralogy, 7th Ed.,

Vols. I and II, Wiley, New York, 1944.

LABORATORY EVALUATION OF

FLOTATION REAGENTS

Mining Chemicals Handbook

Section 4 Guidelines for laboratory evaluation

of flotation reagents

Laboratory flotation testing is a costly and time-consuming process.

The need to produce quality results and, more importantly, accurate

and concise conclusions from the resources invested is vitally

important. Therefore, to produce meaningful and useful data in the

lab, a systematic investigation using good experimental techniques

and consistent laboratory testing procedures must be followed.

The information presented here is not meant to be exhaustive and

should be used only as a guideline. Experience and intuition play

an important role in the evaluation of a flotation process. The

following procedures are discussed in this section:

•

SSaammpplliinngg

– samples should be representative of plant feed/ore type

•

MMiiccrroossccooppiicc aannaallyyssiiss

– to determine mineralogical associations

and degree of liberation.

•

OOrree pprreeppaarraattiioonn

– representative sub-sampling and handling of

ore for flotation evaluation

•

GGrriinnddiinngg

– to achieve desired liberation of value minerals

•

TTeesstt ddeessiiggnn

– to incorporate clear, measurable objectives.

Statistical vs. traditional approach.

•

FFlloottaattiioonn

– screening of reagents and other variables for improved

metallurgical performance

•

HHaannddlliinngg ooff fflloottaattiioonn pprroodduuccttss

– sub-sampling to provide samples

for assays.

•

AAssssaayyiinngg

– to generate mass balances to evaluate flotation

performance

•

DDaattaa aannaallyyssiiss//IInntteerrpprreettaattiioonn ooff rreessuullttss

– to determine if objectives

have been met and provide direction for additional tests.

A. Sampling

When ore samples are taken directly from the mine or a stockpile,

it should be borne in mind that no two ore bodies are the same,

and that variations within an ore body are also common. Close

consultation among the milling, mining and geology departments is

essential to ensure that the sample is as representative as possible.

Reproducibility of flotation test work is paramount to the evaluation

of flotation reagents. Generally, the sample should be sufficiently

Laboratory evaluation of flotation reagents

large so that an entire investigation can be completed on one

sample without having to re-sample the deposit.

In the case of operating plants, samples may be taken from the

conveyor belt feeding coarse ore to the grinding section (e.g. rod

mill feed). Samples should be taken over a sufficient period of time

so that the ore will be representative of current mill feed.

When taking pulp samples it is advisable to verify that the plant is

operating under normal conditions. It is recommended that fresh

pulp samples be taken daily, since the ground ore is subject to aging

effects. The objectives of the test work will dictate the sampling

point and whether to turn off reagent additions prior to sampling.

B. Microscopy

Microscopical examination of the feed samples, which is often

neglected, is essential in the design of the test program and reagent

selection. The feed samples should be examined by a qualified

microscopist/mineralogist, using the appropriate techniques, to

identify the type and mode of occurrence of minerals and their

degree of liberation from each other (see Section 3).

C. Ore preparation

Dry ore

The dried ore sample must be transported to the test laboratory as

quickly as possible and preferably in a coarse state (≥1-2 cm) to

keep oxidation to a minimum. The sample is then typically stage-

crushed to minus 1-2 mm then split manually using a riffle or a

rotary splitter to obtain flotation charges of the desired weight.

The ore charges should then be sealed in plastic bags and stored in

a freezer (preferably -15°C or lower) to retard oxidation/aging

effects. Several randomly chosen samples should be submitted for

assay to confirm that sample splitting has been conducted properly

and that the samples are representative.

Pulp samples

The amount of pulp sample taken at any one time is dependent

upon many factors. These include percent solids of the pulp, the

size of the laboratory flotation cell, the number of flotation tests to

be conducted in a particular series, and the degree to which the

pulp is known to be sensitive to aging effects. Sub-sampling of the

pulp into flotation charges can be done either volumetrically or,

preferably, gravimetrically while the pulp is being adequately agitated.

When the situation is such that the pulp has to be used for an

extended test series, then the test charges should be placed in

sealed containers and stored in a freezer.

Mining Chemicals Handbook

D. Grinding

Laboratory grinding tests are conducted primarily to establish the

size distribution of the solids, which is dictated by the objectives of

the test work.

Mesh of liberation

This is estimated by examining various screen size fractions of the

ground ore (usually the coarser fractions) using reflected light

microscopy. This provides information on the modes of occurrence

and the degree of liberation of the desired minerals i.e. sulfide-

gangue mineral associations.

When microscopical facility or expertise is not available, the

optimum liberation size can be estimated from a granulometry vs.

flotation recovery curve (see F).

Granulometry versus grinding time relationship

By graphically plotting the cumulative weight percent passing (or

retained on) a screen size vs. the log grinding time, a relatively

straight line will result between about 15% and 85% cumulative

weight for that screen size. It is then a simple matter to change the

grinding times during the test program in order to change the

flotation feed granulometry.

Experience at Cytec favors the use of a rod mill for laboratory

batch grinding to minimize tramp oversize and sliming. The pulp

density for grinding is generally in the range of 60% to 70% solids,

depending on the ore's pulp viscosity and the specific gravity of the

dry solids.

The ground pulp should be wet screened on a 200 mesh (74 µm)

or 325 mesh (44 µm) sieve and the oversize and undersize (slimes)

material filtered and dried separately. The oversize is then dry-

screened on a series of sieves generally from about 500 µm through

74 µm or 44 µm (depending on the original size used for the wet

screening). Any material passing through the finest sieve should

be added to the undersize from the wet screening operation. The

weights of the various screen fractions are then used to determine

the size distribution of the ground ore. Stainless steel sieves are

recommended for most routine screening.

E. Test design

Prior to undertaking any extensive reagent-screening program,

the objectives for such a program should be clearly defined.

The variables (i.e. collector type, collector dosage, frother type, pH

etc.) to be studied should be well thought out along with the levels

Laboratory evaluation of flotation reagents

of treatment to use in order to observe the desired response and to

determine the relative importance of these variables. A thorough

investigation of all the variables involved in a process is not practical.

The variables selected for study will depend on the response under

investigation as well as feedback as the investigation progresses.

Variables not under investigation should be kept as constant as

possible.

In some cases the traditional approach of changing one variable at

a time is adequate, but in most cases an experimental design based

on statistical principles is recommended. This enables the researcher

to investigate the effects of several variables simultaneously. Carefully

planned experiments conducted in this manner will provide more

information than the traditional approach and with a smaller

number of tests.

There are many references to statistical experimental designs in the

literature. Cytec’s field representatives have been appropriately trained

in developing experimental designs and can assist the customer in

this respect. For additional information, refer to Section 12.

F. Flotation testing

In designing a flotation test program, experience plays an important

role in minimizing the number of variables and the range over

which these variables need to be tested. Knowledge of how other

plants are treating similar ores is a valuable tool for the metallurgist.

Cytec personnel offer this experience and knowledge as a result of

metallurgical investigations conducted at many plants and with

many ores from around the world.

A number of factors will require evaluation in a flotation test program

1. Grind-granulometry

The grinding range to be evaluated will be largely influenced by

the microscopical examination of various screen fractions,

referred to previously. Because of the operating costs associated

with grinding, a common plant practice is to grind as coarsely as

possible without sacrificing rougher recovery; the rougher con-

centrate then requires regrinding for adequate mineral liberation

prior to cleaner flotation. Evaluation of regrinding should be

conducted using the information presented in Section D. Proper

selection of collector combinations may allow utilization of a

coarser grind without loss of rougher recovery.

1. In the case of complex ores where recovery of two or more

mineral values into separate concentrates is desired, coarse

Mining Chemicals Handbook