USAC has a comprehensive quality control program for the production of antimony
oxide. The control program includes (1) carefully sourcing raw materials with
low impurities, (2) the campaigning of single lots with no commingling of other
lots, (3) the dedication of one production line for one product, (4) the removal
of impurities, (5) the careful adjustment of production controls, (6) the
detailed monitoring of product for color, size, impurities, content, and other
physical, mineralogical, and chemical parameters, (7) careful labeling of all
products, (8) packaging, and (9) a statistical product control system (SPC).
Composite samples for each lot are kept in a library for
A Fisher Sub-Sieve Sizer (FSSS) is used in the
plant for the control of the median particle size. A Micromeritics Sedigraph is
used for particle size distribution. Color determinations are made using a Data
Color Microflash colorimeter. An X-Ray diffractometer (XRD) is used to determine
valentinite. Higher valence antimony oxides are determined by ethylene glycol
digestion. Trace elements are determined by inductively coupled argon plasma (ICP),
and by X-ray diffraction (XRE) using a Niton XL3t with Golld technology. The XRF
is calibrated for specific matgricies using the ICP.
11 October 2011-USAC METHOD
(Notice: this method also titrates iron and is unreliable for most low grade
ores and mill tails where we use ICP and XRF)
Weigh 1.0 gram for
mill tails, leach residue; slag; 0.5 grams for wet or dry sodium antimonite,
low-grade ore; 0.2 grams for hand sort, metal, and mill concentrates.
THE SAMPLE SHOULD BE CRUSHED, SPLIT, PULVERIZED, AND
HOMOGENIZED IN A CERAMIC MORTAR AND PISTIL SO THAT IT WILL ALL PASS A 100 MESH
Place in wide mouth
500 ml Erlenmeyer flask with 25 mls of concentrated sulfuric acid.
Set the flask on a
hot plate adjusted to 100-105 degrees centigrade and digest for at least 45
minutes until the white fume reaches the top of flask.
THE DIGESTION IS EXTREMELY IMPORTANT. IT CAN PROCEED MORE
THAN 45 MINUTES BUT SHOULD NOT BE TAKEN TO DRYNESS.
Add 1 small spatula
(approximately 200 mgs) of hydrazine sulfate 3 times at least at 5-minute
intervals. The hydrazine sulfate reduces all the antimony to the plus three
valence. It is important to fume for at least 20 minutes after the last
addition of hydrazine sulfate to ensure that all the hydrazine sulfate (a strong
reducing agent) has been used up. If this does not happen, you will be
titrating the hydrazine sulfate and you will not reach an end point. Do not
evaporate to dryness.
refluxing reaches top of flask. (When white smoke reaches top of flask and
small rivulets of water run back down in flask).
Cool. Wash down
sides of flask with 25 mls. of water and 40 mls. of concentrated hydrochloric
Boil 3 minutes.
This volatilizes the arsenic.
Cool and wash down
sides of flask with water diluting to 300 mls.
Filter heads and
tails before titration.
Add 20 mls. of
concentrated hydrochloric acid and titrate.
TITRATION SHOULD BE DONE WITH A MAGNETIC STIRRER.
Titer X Factor
X 100 = % Sb
Titer X Factor
X 1,000 = g/l
First all the
antimony is reduced to the plus 3-valence state. On titration, it is oxidized
to the plus 5-valence state.
To prepare the titer
add 2 grams of potassium permanganate per liter of water.
(Approximately 0.004 grams
of antimony/1 ml of titer)
3. To standardize
titrate 0.25 grams of antimony metal 3 times to determine the factor.
THE VOLUME AND USAGE OF THE TITER, IT SHOULD BE RESTANDARDIZED MONTHLY OR MORE
1. Fume hood.
2. 500 ml wide mouth Erlenmeyer flasks.
4. Triple beam balance.
5. Balance accurate to 1 mg.
6. Hot plate
7. Cooling tray.
8. 1000 ml. volumetric flask.
9. 100 ml graduated cylinder.
10. 50 ml. burette.
11. Burette stand with white stand.
12. Wash bottle.
13. Weighing papers.
14. Filtering funnel and paper.
15. Filter stand.
16. Steel mortar and pestle.
17. Ceramic mortar and pestle.
19. Laboratory jaw crusher.
20. Sample splitter.
21. Sample journal.
1. Sulfuric acid.
2. Hydrochloric acid.
3. Hydrazine sulfate.
4. Potassium permanganate.
5. Boiling crystals.
6. CP antimony metal.