Writings

All the photos in the above artcle were taken by me during a research trip to the Henderson Mine

Mine Tram

By Walter Weart

The last run of the Henderson Mine railroad took place July 30, 1999 marking the end of a little known but unique industrial railroad. The Henderson had one of the longest rail tunnels in world and only its remote location in the Rocky Mountains kept it out of the spotlight. This heavy haul, electrically powered railroad transported more than 150 million tons of ore during its 23 year life. It has since been replaced with the world's longest conveyor belt operation but not before achieving some remarkable statistics.

The Climax Molybdenum Company, operator of the Henderson mine and part of Phelps Dodge Co., was chartered to develop the deposit of molybdenum which was discovered in 1964. The ore body is located inside Red Mountain near Empire, Colo., about 50 miles west of Denver. Molybdenum or "Moly" as is it more commonly called, is a basic ingredient in certain types of steel, automotive airbags, a smoke retardant in plastics and fibers and is used as a catalyst in oil refining.

Development of the deposit began in 1970 and by 1976, production had started. The initial work was at the 8,100 foot level and it, along with the now exhausting 7,700 foot level were served by the mine train operation. The levels of elevation are based on sea level. The mountain is laterally mined from the top down and the inside out.

The rail line was the engineer's answer to the question of how to move molybdenum ore from a mine inside Red Mountain to a processing mill about 14 miles away on the other side of the Continental Divide. Given the tonnage to be moved and distance to be covered, a railroad was the only real answer. The rail operation required a tunnel under the Continental Divide that is 9.8 mile long, longer than either the BNSF's Cascade tunnel or the Union Pacific's Moffat tunnel. One source ranks the Henderson tunnel is 10th longest in the world.

Once the decision was made to build the railroad, selection of power and equipment was next. With a 9 mile tunnel, diesel power was not practical unless an expensive ventilation system would have been used. The density of train operation also made diesels undesirable since the trains would be manned and the fumes would have been dangerous.

Sweden's ASEA was chosen to supply 32 electric engines or "locis" as they are called by the Henderson personnel. Each loci weighed 55 tons and rode on two axles. The technology used was based on the rail equipment used in Europe and the gauge chosen was 42 inch, similar to that of many European lines. Catenary style overhead was used and the engines were dual voltage operating on both 1,400 volts and 600 DC volts. For safety reasons, given the close clearances inside the mine, voltage in the loading areas was limited to 600. The trains used disc type air brakes along with dynamic braking, a common feature on electric operations.

Henderson also rostered 3 small diesels which were used for work trains as well as for movements over the small amount of non-electrified trackage. One of these was retained after the electric operation was shut down. The conveyor is bolted to the outbound track and the inbound track is retained in the tunnel for maintenance purposes. This diesel will be used as needed.

Approximately 250 20-ton ore cars were also purchased and these also rode on two axles as did the engines. The cars are dump bottom and used a unique unloading system. As the cars passed through the unloading facility, they were suspended on wheels mounted on each side of the unloading pit. A flange on each side of the car rode on the wheels. This allowed a wide open dump pit, unhindered by rail or supports.

A guide rail under the cars opened and closed the bottom of each car allowing complete unloading to be done very quickly. Even the engines were equipped with these flanges so they were also momentarily suspended over the pit. With locis at both ends of the train, continuous movement was possible.

The line was double track with a series of loading tracks at the mine and a small yard behind the unloading building at the mill. The track was originally a combination of 90 and 115 pound rail but the lighter rail was gradually replaced with the heavier rail over time on the outbound track. The track in the tunnel was mounted on a concrete slab with pandol plates and clips. The outside track was on conventional wood ties. The track in the tunnel is on 3 percent grade and this presented some real operating problems. The grade was against loaded trains and because of this, the rail actually flowed or stretched downhill towards the mine. There was a special switch at the bottom of the grade which allowed the rail to stretch and the excess rail was periodically trimmed.

Various combinations of engines and cars were used until a pattern of 3 locis on one end and two on the other spliced by 30 cars became standard. Top speed was about 25 miles per hour and the round trip took about two hours. Until 1996, each train had an operator until an automated system was installed. The original automatic block signal system was incorporated into the new system. 3000 foot loops of wire were installed between the rails along with radio equipment on each locomotive. The system detected the speed and direction of each train while maintaining proper spacing.

The equipment was extremely durable and the locis had an availability rate in the high 80 percent range. The typical operation of the mine was 24 hours, 5 days a week and the trains had to keep moving if the mine and mill were to function economically. Nearly all the cars and engines were still in service on the last day attesting to the quality of equipment and care and maintenance provided by the Henderson railroaders.

As the ore at the 7,700 foot level became depleted, the continued operation of the railroad came under review. The new producing level, located at 7,175 feet or nearly 400 feet below the train level, is too far below railroad to make continued operation possible. The ore would have to have lifted up to the level of the train whereas before the ore was dropped down to the train for loading.

Many options were considered before the conveyor system was chosen. Routing the trains down to the new level would have required a steep spiral grade which would have been beyond the ability of the trains to negotiate. Another plan involved a conveyor from the new level up to the trains but it was also impracticable. Another plan would have used a conveyor from the mining level to the entrance of the tunnel where the ore would have been transferred to the trains for movement the crusher. The final determinate in deciding to replace the rail line with a conveyor system was the age and condition of the cars and locis. "We were dealing with 1960 technology and parts were becoming increasingly difficult to obtain," said Jim Mahon, Maintenance Superintendent. Mahon indicated that they also looked into replacing the existing equipment and the cost of the trains and conveyor belt came in about the same but the maintenance expense for the belt was less than the railroad.

After the decision was announced the Henderson staff allowed the Rocky Mountain Railroad Club the opportunity to make two visits to the railroad and photograph the above ground operation. A film crew was allowed to videotape the entire operation including cab rides in the locis. After the trains were shut down, the Henderson staff donated a loci and a mine car to the Western Museum of Mining and Industry in Colorado Springs, Colo. In addition to donating the rolling stock, the Henderson donated the transportation to the museum as well. Future plans call for the loci and car to be displayed on a section of track under catenary so it will look as it did when in service. Another loci and car have been preserved at the entrance to the mill complex.

While the conveyor belt is more efficient and cost effective, it is a safe bet that no one will feel about it as they did about the Henderson mine tram.