Mineralogy
1.1 MINERALOGICAL OBSERVATIONS
Bacon, Donaldson & Associates Ltd. (BD&A) was retained by Canadian Mine Development in 1988 to complete a mineralogical and metallurgical investigation for the Tel, Discovery, and Kim Deposits. A basic mineralogical investigation was completed to determine the gold associations and determine the reasons for less than 100% recovery of gold by the cyanidation process.
1.1.1 SAMPLE PREPARATION
Three samples of each ore type (Tel, Discovery, and Kim) were tested and polished samples were produced. The flotation concentrate and "head" samples have the chemistry as shown in Table 1 (Henrioulle & Bacon, 1988a).
Table 1 Chemistry of Head and Flotation Concentrate Samples (Henrioulle & Bacon, 1988a)
| POLISHED SECTION
| ASSAY
|
Au
oz/ton |
Ag
oz/ton |
Fe
% |
S
% |
As
% |
Cu
% |
Zn
% |
| TEL HEAD |
1.176 |
2.491 |
17.7 |
17.0 |
3.85 |
0.30 |
6.32 |
| DISCOVERY HEAD |
0.756 |
1.050 |
15.4 |
12.9 |
2.61 |
0.07 |
1.59 |
| KIM HEAD |
0.339 |
0.588 |
7.4 |
7.4 |
2.04 |
0.07 |
1.07 |
| TEL FLOT. CONC (A) |
4.296 |
8.572 |
38.0 |
43.5 |
3.64 |
0.72 |
- |
| DISCOVERY FLOT. CONC (H) |
3.808 |
4.658 |
44.4 |
45.8 |
4.40 |
0.22 |
- |
| KIM FLOT. CONC (M) |
2.040 |
3.582 |
39.0 |
43.0 |
5.52 |
0.35 |
- |
1.1.2 RESULTS
Gold electrum particles typically occur from fine (>1 micron) to coarse sizes (>40 micron) with occurrences of much larger particle sizes as shown in the 1986 Micrograph images in Figures 1, 2, 3, and 4 below. Through the use of microscopy, it is determined that gold is mainly associated with sulphides, predominantly pyrite. There have also been observations that gold is sometimes associated with arsenopyrite. Descriptions of the gold occurrences in the various samples are detailed in Table 2 (Henrioulle & Bacon, 1988a).
Table 2 Description of Gold Occurrences for Various Sample Types (Henrioulle & Bacon, 1988a)
| Sample Type |
Gold Occurrence Description |
Tel Flotation Concentrate |
- Typically gold is electrum in pyrite or in a matrix.
- Very fine veinlets (0.1 to 0.2 microns in width) of electrum also observed.
- Gold within the narrow veinlets will typically not cyanide even with fine grinding.
|
Discovery Flotation Concentrate |
- Gold often occurs as fine electrum particles of which some are middlings with pyrite and arsenopyrite.
- Veinlets of gold are also observed, see micrograph in Figure 16-1.
|
Kim Flotation Concentrate |
- Gold typically occurs as coarse particles, which are easily cyanidable electrum particles.
- Gold is mainly associated with pyrite; see micrograph in Figure 16-2 and Figure 16-3.
- Minimal occurrence of gold in small veinlets that is not conducive to cyanidation.
|
Tel & Kim Cyanidation Residue |
- SEM-EDS microscopy did not reveal occurrences of gold.
|
Discovery Cyanidation Residue |
- Very fine gold particle (non-electrum) contained within a gangue particle observed with SEM-EDS (one occurrence observed).
- Particle was too fine to be liberated by grinding.
|
The mineralogical observations support that flotation results in high gold recoveries. Gold that is not a free electrum predominantly occurs as middlings with easily floated sulphides. The mineralogical observations also support the slightly lower cyanidation results. The small percentage of very fine occluded gold and electrum particles in sulphide and gangue matrices are unavailable for cyanide dissolution and thus are not conducive to recovery through cyanidation processes. Conclusions were also drawn that finer grinding would not improve the recovery through cyanidation processes of the very fine occluded gold and electrum particles (Henrioulle & Bacon, 1988a).
