AGGLOMERATION

A SHORT NOTE ON AGGLOMERATION
Agglomerates are particulate materials consisting of large particles formed by the joining or binding together of primary particles whose original identity can still be visible in the final agglomerate form. The term can refer to: Cluster of primary particles held together by weak physical interactions Cluster of molecules or particles that results from agglomeration Scrambled auto-assembly of otherwise isolated single molecules or particles Cluster of primary particles interconnected by chemical bonds.
Agglomeration of corrosion products in boilers increases scale buildup, which leads to corroded boiler walls and heat loss. Agglomerate is also known as flocculate, aggregation, coagulation and coalescence.
An agglomerate is a material formed by objects sticking together and forming clumps. A common example is when mixing powders into liquid, the powders often form clumps, requiring some mechanical effort to break apart.
In surface chemistry, agglomerate is the process by which fine particulates are caused to clump together into a floc. The floc may then float to the top of the liquid (creaming), settle to the bottom of the liquid (sedimentation), or be readily filtered from the liquid.
Agglomerates are affected by several parameters, including:
Mixing speeds
Mixing intensity
Mixing time
Agglomeration and sedimentation are widely employed in:
Purification of drinking water
Sewage treatment
Storm-water treatment
Treatment of other industrial wastewater streams
Agglomerates can cause corrosion. For example, in process water systems, corrosion products agglomerate significantly in certain locations. Significant agglomerations (or deposits) can occur in copper cooling passages and where heat is removed by water cooling. Such agglomerations also occur at restrictions found in non-copper system components like valve seats, fixed orifices, pump seal faces, etc. Agglomerations causes component clogging and malfunction, which leads to increased corrosion rate.
Agglomerates also cause sedimentation in water treatment plants and scale formation in boilers, which ultimately leads to process inefficiency, corrosion and boiler failure.
As in the case of metallurgy, generally, the success of metallurgical processes depends on the particle size and uniformity of the raw materials used. In the light of beneficiation of low grade ores, the particle size of the concentrates had consistently reduced and hence not suitable directly for metallurgical operations. Thus it become necessary to agglomerate the fine concentrates to make them suitable for subsequent metallurgical operations.
The type of agglomeration process depends on the quality of raw materials used and the quality of agglomerate needed for subsequent operation.
Agglomeration plays an important role in industrial applications as is the case with ferro alloy industry. Since the power consumption in the electric furnace is a major contributor for the cost of ferro alloy production, pre reduction before the ore is charged into the electric furnace reduces the cost of net product made, by lowering of the power consumption in the arc furnace.