mini pelletization plants

The original shaft furnaces were designed for hematite and magnetite ore. And the first furnace designs were either square or round, both of which were not suitable for an equal feed across the bed, therefore with the addition of the moving stockline feeder, the furnace became rectangular. With new electronics and computer applications I have been working on some designs to again incorporate the round furnace since it is much more structurally sound then a square or rectangular furnace and hence cheaper to build.

The first commercial furnaces also were designed for about 100,000 TPY. The largest was built for 500,000 TPY. I believe that even larger furnaces can be built with a round design, perhaps up to 1 million TPY.

The shaft furnace can be operated as the least costly induration furnace for pelletizing iron ore since the heat is contained and can be used as part of the process. With magnetite ore about 1/3 less input energy is used in the shaft furnace as compared to a grate or grate kiln. With hematite ore about 10 to 20% less input energy is used in the shaft as compared to the grate or grate kiln. Of the 4 types of furnaces for pellet induration, the shaft furnace, grate, grate kiln or rotary hearth, the shaft furnace is the cheapest to build and the cheapest to operate, can be built as small as required and up to 1 million TPY as indicated above.

The shaft furnaces went by the wayside as plants became larger and larger, today up to 6 million TPY in a single module. The general cost of a pellet plant in the US or Europe is about US 80 dollars per annual ton of capacity with a sliding scale for capacity. The shaft furnace would be a bit cheaper, perhaps by 25%. In India even cheaper by another 10 to 20%.

The quality of the ore or grind would not change with one type induration plant or the other. The grind is done to separate the components. In a BF pellet the chemistry has to be suited to the BF operation mainly considering silica and iron whereas in a DR pellet the less other materials over iron is best. The DR pellet is more expensive since more grinding is required to reduce other materials.

Since porosity is a key factor in the BF or DR pellet use then again the grind is important to ensure a finished pellet has at least 25% pellet porosity. If the chemical and physical characteristics are met the mesh doesn't matter. However as a general rule of thumb the mesh is normally around 325 and higher than 85%.

All these factors have to be considered in pelletizing, but they do not make a difference in induration from one process to the other.

The Chinese have a modified shaft furnace design since they built it based on pictures they copied and have not been able to put in any type of corrections to their designs. They also do not evenly put materials on the bed but have a single crown effect and hence lose gas flow distribution in the bed. Quality of pellets is much lower and capcity is about 1/2 of plants built be the original designers.

The only company in the world that offers original shaft furnace technology for induration of iron ore pellets is T.C.Inc., email tcinc002@aol.com The only operating plants using shaft furnace technology is in Tasmania, producing over 2 million TPY. One was built in India in the 1990's but was shutdown when they switched over to hematite from magnetite and weren't prepared to convert the process. There are used plant equipments for sale for shaft furnaces. If interested contact us.