Man has been mining stone, metals and minerals since prehistoric times. The world's oldest known mine site is located in Swaziland in Africa, where the first mining of metals was recorded via carbon dating as 43,000 BC. Mining of metallic minerals occurred in ancient Egypt, Greece and the Roman Empire, and metals such as iron ore contributed to the industrial growth of Europe during the Middle Ages. Iron is the fourth most abundant mineral in the Earth's crust, at about five percent, and it also represents 95 percent of all metal used in any given year.
The gold rush of 1849 also drove the need for iron ore, and areas like the Mesabi Range in Minnesota were accidentally discovered while miners were searching for gold. These early days saw miners use shovels and pickaxes to take the ore out of the rock. Horses and mules hauled the ore out of the mine. Later, steam shovels and engine-powered tools were used. Prior to the development of the Bessemer Converter for processing of ore into steel, steel was a very expensive commodity. When the process was introduced in the United States, production skyrocketed and a massive supply network was created to deliver raw materials to the processing plants.
Aggressive transporting of ore by rail began in the 1880s. The ore was shipped through the Great Lakes to ports in Chicago, Detroit, Cleveland, Erie and Buffalo and then shipped by rail to a network of steel mills around the country. This combination of barges moving ore from Minnesota through the great lakes and trains moving coal from Pennsylvania drove the industrial revolution in the United States and provided all the steel used during the first and second world wars. The amount of ore and coal being moved required a huge volume of heavy duty equipment for unloading and transporting the minerals.
Iron ore prices were decided by miners and steelmakers, and the first deal reached became a benchmark for others in the industry. In recent years this system was replaced with a market-based pricing system.
Although most of the mines in Minnesota have now closed, there is still a significant amount of iron ore being transported worldwide. In Australia alone, there is 24 billion tons of iron ore available.
A variety of systems exist for unloading iron ore shipments. By rail, cars filled with iron ore convey their loads to processing sites, directly to blast furnaces or, in the past, to ore docks to be loaded into ships. Today's typical discharge system is the rotary railcar dumper, which turn cars over to spill their contents into pits containing conveyors that carry the ore away to stockpiles.
A dumping cycle begins when a loaded railcar moves into position and the operator initiates the unloading process. The dumper cradle begins to rotate, clamp arms leave their support posts and the clamps begin to descend. By the time rotation reaches 15 degrees, the spill truss supports the side of the car and the clamps have locked onto it. The car is securely gripped and supported throughout the rest of the rotation cycle. By the time the car has been rotated 160 degrees, dumping action has normally been completed. The barrel movement is then reversed and the car returns to the upright position. As this is happening, the clamps release, the platen locks disengage the platen hooks align the platen rails with the yard tracks and the empty car is ready to exit the dumper. Stop, reverse and speed changes are controlled by limit switches for safe and reliable operation.
The fastest unloading times are realized when dumper installations are matched to unit trains of iron ore. To achieve the fastest times and the highest productivity with minimal personnel, railcar dumper unloaders must be matched to support equipment such as train positioners, car indexers, traveling hammermills and track systems designed to handle high numbers of railcars.
When circumstances call for it, railcar dumping systems can be adapted and customized beyond their standard features to match special site or environmental considerations. In this context, these "special circumstances" mean bulk handling requirements that are even more demanding than the accepted standards for trains and railcars. Since iron ore is a heavy, punishing material, it can easily fall into this category. Some operations need an unloader that is robust enough to handle iron ore.
Rotary car dumpers from Heyl & Patterson are cost-effective all-purpose workhorses. Dumping cycle times can be as fast as 35 seconds per car. Tonnage throughput can reach 10,000-plus tons per hour. The rotary dumper is the choice for high speed automatic dumping of both rotary coupled cars and random car applications.
Heyl & Patterson carefully analyzes each potential application to establish peak forces encountered during each phase of iron ore unloading. This ensures the proper sizing of drives, arm configurations and wheel chocks. Precise engineering methodology assures successful operations for many decades to come. Whether the requirements are for today or tomorrow, if it can be loaded into an open-top car, a Heyl & Patterson dumper can empty it. Heyl & Patterson engineering handles the needs of today and the heavier payloads of tomorrow, plus the unforeseeable demands of the future.
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