Timmins Gold Corp.

Timmins Gold Corp.

November 21, 2012 06:00 ET

Timmins Gold Reports Positive Results From Bulk Sample Leach Testing Program at San Francisco Mine

VANCOUVER, BRITISH COLUMBIA--(Marketwire - Nov. 21, 2012) - Timmins Gold Corp. ("Timmins Gold" or the "Company") (TSX:TMM)(NYSE MKT:TGD)(NYSE Amex:TGD) announces a summary of the results from a recent bulk sample locked column leach testing program on material from the Company's San Francisco Mine (San Francisco deposit and La Chicharra deposit) and tested at METCON Research metallurgical laboratory in Tucson, Arizona in 2012.

The column testing results indicate an average gold extraction of 71.0% based on a crush size of 80% of the particles passing 3/8 inch (P80 3/8 inch) and 77.1% based on a crush size of 80% of the particles passing 1/4 inch (P80 1/4 inch) on ore samples from the San Francisco deposit. For La Chicharra ore samples, the column testing results indicate an average gold extraction of 78.3% and 80.9% based on a crush size of P80 3/8 inch and a crush size of P80 1/4 inch, respectively. No percolation issues were observed in the locked cycle tests.

Bruce Bragagnolo, CEO of Timmins Gold, stated, "We are encouraged by the metallurgical results from this recent metallurgical testing program. We will continue to use a Life of Mine (LOM) recovery of 68.6% gold recovery in our planning and analyses, based on our most recent mine plan and block model. We believe however that the results of this testing program indicate there is potential to further improve our recoveries through process optimization."

Discussion of Test Results

Six composite samples were tested in the current metallurgical study; five from the San Francisco (SF) deposit and one from La Chicharra. The samples from the San Francisco deposit varied by rock type.

  • La Chicharra
  • SF - Granite
  • SF - Basic Gneiss
  • SF - Gabbro
  • SF - Pegmatite & Schist
  • SF - Acid Gneiss

Tables 1 and 2 outline the gold extractions for each sample based on crush sizes of P80 3/8 inch (9.5mm) and P80 1/4 inch (6.3mm), respectively. Two averages are shown: (1) a simple average and (2) a weighted average based on the estimated LOM relative abundance of each rock type within the deposit.

Table 1 - Summary of column leach tests, P80 -3/8" crush size, 127 days.
LOM Abundance Au Extraction (%)
SF - Granite 13.0% 76.58
SF - Basic Gneiss 26.4% 71.08
SF - Gabbro 18.9% 63.78
SF - Pegmatite & Schist 12.7% 74.38
SF - Acid Gneiss 29.1% 71.40
SF - Simple Avg. 100% 71.44
SF - Weighted Avg.
(based on LOM abundance) 100% 71.00
La Chicharra 100% 78.34
Table 2 - Summary of column leach tests, P80 -1/4" crush size, 127 days.
LOM Abundance Au Extraction (%)
SF - Granite 13.0% 87.89
SF - Basic Gneiss 26.4% 74.37
SF - Gabbro 18.9% 71.22
SF - Pegmatite & Schist 12.7% 79.69
SF - Acid Gneiss 29.1% 77.03
SF - Simple Avg. 100% 78.04
SF - Weighted Avg.
(based on LOM abundance) 100% 77.06
La Chicharra 100% 80.89

The common leaching parameters to all column leach tests are summarized below:

  • Sample sizes were ~178kg for each column test.
  • Calcium oxide was blended into the test charge. Calcium oxide consumption was determined in a 72 hr agitated cyanidation bottle roll test.
  • The initial feed solution was prepared by adding reagent grade calcium oxide to Tucson tap water to obtain a solution pH of 11.00, followed by the addition of 1.0 gram of sodium cyanide per liter of solution. The columns were irrigated at a flow rate of 10 liters per hour per square meter.
  • Column tests were conducted under locked cycle type of leaching regime by contacting the pregnant solution with activated carbon to remove gold and silver in solution. The loaded activated carbon in each column test was dried, weighed and saved in sealed and labeled plastic bags.
  • The resulting barren solution was used as feed solution after the addition of sodium cyanide and calcium oxide to maintain 1.0 gram of cyanide per liter of solution and a pH of 10.50 to 11.00.

Quality Control

As part of the METCON QA/QC program, approximately 10 percent of the daily pregnant solution samples from each column test were re-assayed to verify accuracy of the original gold and silver assay conducted on the daily pregnant solution samples. Linear regression analysis was conducted to quantify the difference between both assays. The following table summarizes the QA/QC analysis conducted on the pregnant solution samples.

Table 3 - Correlation coefficient, Daily pregnant solution vs. Duplicates
R2 Correlation Coefficient
Au Ag
SF - Granite 0.9596 0.9539
SF - Basic Gneiss 0.9563 0.9445
SF - Gabbro 0.9842 0.9729
SF - Pegmatite & Schist 0.9808 0.9738
SF - Acid Gneiss 0.9277 0.9086
La Chicharra 0.9696 0.9970

The linear regression analysis conducted on the pregnant solution assays showed that there is a good correlation between the original gold and silver assays and the duplicate assays conducted as part of the METCON QA/QC program.

About Timmins Gold

Focused solely in Mexico, Timmins Gold Corp. is in commercial gold production at its wholly owned San Francisco gold mine in Sonora, Mexico. The mine is a past-producing open pit heap leach operation. Timmins Gold has forecast production at a rate of approximately 130,000 ounces of gold per year (Micon International NI 43-101F1 Technical Report dated November, 2011).

This press release was reviewed and prepared by Lawrence A. Dick, Ph.D., P.Geo, who is a consultant to the Company and is recognized as a Qualified Person under the guidelines of National Instrument 43-101 ("QP") and by Miguel Soto, P. Geo., a director and the Vice President of Operations of the Company and by Rodrigo R. Carneiro, MS., QP in Metallurgy and Processing, Director of Metcon Research and Process Engineering of Tucson Arizona. For further information contact Timmins Gold Corp. at 604-682-4002 or go to the website at www.timminsgold.com.

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