1. Sodium Oleate Concentration
TANNINS IN MINERAL PROCESSING AND EXTRACTIVE METALLURGY
Jordan Rutledge & Dr. Corby Anderson
Colorado School of Mines
Research Objective
Scope
Microflotation
Microflotation
Problem
Quebracho has been used for decades in mineral flotation; however, why quebracho is successful in the separation of ores is still vague.
Motivation for Work
The goal of this research is to provide a better understanding of how quebracho can be used to separate gangue from valuables and why it is effective. The research is conducted from the bottom up by identifying surface chemistry interactions and applying the gained knowledge to bench scale flotation.
Collaboration
This research is being done through the Colorado School of Mines in collaboration with Silvateam Inc.
The focus of this work is on the use of quebracho tannin as a depressant for mineral flotation—specifically fluorite and copper ores. [4]
Microflotation: used to determine a quick flotation response on pure minerals to predict optimal flotation conditions.
There are many factors in flotation that are controlled. Small changes can lead to a significant difference in recovery and grade. The six factors above were manipulated in this study to observe the flotation response using statistical software. Figures 4 and 5 display the fluorite recovery comparing quebracho and wattle tannins. It can be seen that the quebracho tannin has a higher recovery than that of wattle. The highest recovery of fluorite with quebracho was recorded to be 92% whereas it was 89% at the same conditions with wattle tannin.
Figure 4 & 5. Statistical models of the quebracho and wattle tannin use in fluorite microflotation tests.
Calcite depression was best improved with the addition of quebracho as shown in Figures 6 and 7. Only 5% of calcite was recovered in the concentrate with quebracho wheras 10% was recovered using wattle tannin.
Figure 6 & 7. Statistical models of quebracho and wattle tannin use in calcite microflotation tests.
Frother
Condition Time
Sodium Oleate Concentration pH
Characterization: MLA analysis, x-ray diffraction, liberation & size analysis, total carbon & total sulfur
Fundamental surface chemistry: zeta potential, adsorption density, and microflotation
Concentration studies: flotation on 2 liter Denver cells
Stage 1
Tannin Concentration
Stage 2 pH
Stage 3
Tannins [ppm]
Background
Characterization
What are tannins? Tannins are an organic compound found in trees that are composed of phenols, made up of the phenyl and hydroxyl groups, and have the molecular formula of C6H5OH. [1]
Figure 1 & 2. Quebracho tree and chemical structure. [2,3]
A characterization of a Mexican fluorite ore was done by Gary Wyss at the Center for Advanced Mineral & Metallurgical Processing. Below shows the results for the Mexican fluorite ore.
FLUORITE
Figure 3. MLA image from 210 x 297 micron fraction. pH
Tannins [ppm]
P80: 400 μm
Best liberation size: 210 μm
Total carbon: 3%
70% fluorite, 23% calcite, 4% quartz,
2% dolomite
Future Work pH
Bench scale laboratory tests will be done on a several fluorite ores using Denver 2L cells.
Figure 7 & 8. Denver flotation cell and sulfide flotation. [5,6]
In addition to the fluorite work, a full flotation study will be conducted for the influence of quebracho on the depression of pyrite in copper ores.
Tannins [ppm]
ORES TANNINS ARE USED ON:
Fluorite
REO
Copper
Nickel
Iron
Zinc
Tin
Lead
Strontium
Tungsten
Gold
Germanium pH
References
[1] A. Cannas, 'Tannins: fascinating but sometimes dangerous molecules', Cornell University: College of Agriculture and Life Sciences, [Online]. Available: [Accessed: 13- Feb- 2015].
[2] Pubchem.ncbi.nlm.nih.gov, 'Quebracho | C26H20O18 - PubChem', [Online]. Available: [Accessed: 13- Feb- 2015].
[3] V. Pillar, ‘Desmonte quebracho colorado.’ 2005.
[4] J. Rutledge; C.G. Anderson, “Tannins in Mineral Processing and Extractive Metallurgy.” Metals (2015). [Online]. Available: [Accessed: 2-Nov-2015].
[5] Sepor. Laboratory Flotation Machine. [Online] Available: machine-d-12/. [Accessed: 30-Aug-2015].
[6] AMML Flotation. [Online] Available: [Accessed: 2-Nov-2-15]
Tannins [ppm]