(16) 1915 Mine Productivity Determination

I conducted an historical review on a small local Gold Mine and during the research I found an actual evaluation of the production of the mine completed in April 1915 by a local geologist. I have developed two slides that show the production values of the mine.

The first table below discussed the Mine Assay Values. Four samples were taken from various locations in the mine and assayed for gold and copper, the prevalent ores in the mine. Each sample was analyzed and they came up with a dollar value per ton. Today we use ounces of the ore instead of dollar value since metal prices fluctuate quite a bit. As noted on the table the 1915 gold and copper values were $21 per ounce for gold and $0.08 a pound for copper. I made up a second column for the gold and copper prices in 2012 with gold being at about $1,700 per ounce and copper being approximately $3.55 per pound. You can see that the average per ton was $27 and at today’s prices it would be $1,500 per ton. The results were that the mine had some good ore values.

He went on to determine if the mine operation could continue on the ore values that were found. This is where the second table below for Mine Production was used. This takes into consideration all of the individual operating costs. It is interesting to see how much each component would cost in 1915. To find out what the comparable prices would be today I used the Consumer Price Index (CPI) for today as compared to 1915. The factor was $1 in 1915 which would be worth $23 today. I developed a second column and used the price of each item times 23 to get the cost today.  The engineer totaled each of the individual cost of mine operations. Once he had those figures the mining mechanism, a 10-stamp mill, was factored in to determine how much ore could be processed. It was determined that the mill could process 30 tons per day. The profit was determined by subtracting the mine operating cost per ton from the mine production per ton and multiplying that number by 30. The geologist determined that the values obtained were adequate for the mine to stay in business. The actual operating cost today will be more, in that, there are other costs that are included such as reclamation costs that were not in place in 1915 and would make the final cost of operations much more and the total profit less.  

       

(15) American Boy 10-Stamp Mill Progress

I have been involved with the restoration of this 10-stamp Mill at the Mojave Desert Heritage & Cultural Association in Goffs, California. The restoration was started about three years ago and is proceeding well.

We last worked on the American Boy stamp mill on the weekend of April 11 through April 14:  There were (9) volunteers that participated in the significant progress made that weekend. The following work was completed:

Transition Deck Installation The purpose of the transition deck is to allow operators to access the upper ore bin deck from the back of the mill and walk around to the operator’s deck. This keeps the front of the stamp mill visible and eliminates the need for a pair of stairs in front of the mill. The picture below shows the transition deck being installed: 

Railing and Kick Plate Installation Railing had to be installed to keep the operators from falling off the deck and keeping them clear of the rotating equipment. The 6” kick plates along the base of the walkway keep tools and other items from falling on personnel under the deck. 

Installation of the Staircase The staircase was donated by the Superstition Mountain Museum, Apache Junction, Arizona. The staircase had to be modified to overlap the deck and assure that the staircase would be securely anchored to the upper deck. There was also a platform constructed to set the bottom of the staircase. The platform is not shown in this picture. 

Finished Transition Deck and Access Staircase The deck assembly went off with great success. The deck allows access to the operator’s section and protects the operators. 

Jackshaft Stiffener Installation The jackshaft moved slightly when running the mill, so railroad ties were used with concrete anchors to stiffen the jackshaft. The modification was a great success making the jackshaft “rock steady” during mill operation.  

Detroit Diesel engine The engine pulley was changed to a smaller pulley to allow the engine to run at its optimum speed (approximately 2000 RPM) and have the speed of the bull wheel at about 60 RPM. When the engine was run it sounded much better and will significantly improve the life of the engine. The engine was moved further away from the deck to allow better utilization of the engine adjustment. The engine was run twice and the bull wheels engaged. The belts tracked well and the overall operation is ready to start dropping shoes after the idler pulleys are installed. 

A presentation was made after the Saturday Evening Dinner. FedEx Express in Irvine, California donated drive belts for the American Boy Stamp mill. They also donated belts to two other museums. The picture below shows the collage of pictures of the Goffs American Boy 10-stamp mill, Cave Creek’s Golden Reef 10-stamp mill and Superstition Mountain Museum’s Cossak 20-Stamp Mill. In the picture from left to right we have Roger Camplin representing Superstition Mountain Museum, Nance Fite representing FedEx, and the recipient of the collage, Hugh Brown the Executive Director of the Mojave Desert Heritage & Cultural Association and finally Charlie Connell (author of stampmillman) representing Cave Creek Museum. 

The following are some additional pictures of the status of the mill in late April 2013. We are expecting the mill to be operational by September 2013.