Iron ore beneficiation plant

Iron ore processing

In earlier mechanised opencast mines, processing involved was crushing to required size and separation of various products by dry screening. With the increasing emphasis on cleaner product, wet screening has come in vogue in place of dry screening. Small capacity crushers have now given place to large capacity crushers with improved reduction ratio. From Jaw crushers, mine operations have switched over to gyratory and cone crushers where closely sized materials are required. Since steel plants are switching over to sinter, iron ore fines are now finding market and full recovery of these fines, classifiers, hydro cyclones and filters are increasingly used. For obtaining iron ore concentrates from low grade ore various processing routes of gravity separation, flotation and magnetic separations are in practice through out the world and India too.

Iron ore is converted into various types of iron through several processes. The most common process is the use of a blast furnace to produce pig iron which is about 92-94% iron and 3-5% carbon with smaller amounts of other elements. Pig iron has only limited uses, and most of this iron goes on to a steel mill where it is converted into various steel alloys by further reducing the carbon content and adding other elements such as manganese and nickel to give the steel specific properties.

Stamp mill beneficiation equipment

Smaller material would slide across the “grizzly” into the crusher. The larger pieces of ore passing into the crusher would remain until they were pounded into a workable size (less than 2 inches) then fall into the ore chute. Once the mercury on the recovery table was full, or the ore run was complete, the gold and mercury would be scrapped off the table and separated. Separation would be accomplished by straining the amalgam mixture through a chamois. Further separation could be done by a retort process. The retort would heat the mercury removing it from the gold as vapor and condensing it for later use. The remaining gold was now in amalgam form, ready for further refinement processes such as smelting into bullion.

A stamp mill consists of a set of heavy steel (iron-shod wood in some cases) stamps, loosely held vertically in a frame, in which the stamps can slide up and down. They are lifted by cams on a horizontal rotating shaft. On modern mills, the cam is arranged to lift the stamp from the side, so that it causes the stamp to rotate. This evens the wear on the shoe at the foot of the stamp. As the cam moves from under the stamp, the stamp falls onto the ore below, crushing the rock, and the lifting process is repeated at the next pass of the cam. Each one frame and stamp set is sometimes called a “battery” or, confusingly, a “stamp” and mills are sometimes categorised by how many stamps they have, i.e. a “10 stamp mill” has 10 sets. They usually are arranged linearly, but when a mill is enlarged, a new line of them may be constructed rather than extending the line.

Iron ore beneficiation plant

Raw iron ores are crushed by jaw crusher, then get a reasonable degree of fineness iron ore. These relatively small iron ore particles enter ball mill for grinding through the elevator and vibrating feeder. After ball mill grinding, the milled ore gets the next procedure: classification. Because of different proportion of solid particles in the liquid precipitation at different speeds of the principle, spiral classifier clean and grade the iron ore mixture.

Extensive testwork over a 2-year period combined with robust industrial mining technologies and clever design have resulted in a cost-effective beneficiation process plant design for OneSteel’s new Iron Baron project. The challenge for this project was managing the high variability of the low-grade stockpiles. Mineral Technologies’ know-how and experience in metallurgical testwork was a key part of the solution, uncovering a number of beneficiation options. The extensive testwork delivered a process design utilising the latest HC33 gravity separation spiral technology to achieve a cost-effective solution.