Ispat Industries Limited's highly advanced cold rolling mill at Kalmeshwar was set up in 1988, in technical collaboration with Hitachi of Japan, to manufacture cold rolled carbon steel strips in a wide range of thickness and width. The mill has a capacity of 3,25,000 tonnes per annum (TPA) and comprises various processing units as mentioned below:

Continuous Pickling Line
The hot rolled coil, which is the basic raw material, is passed through the Continuous Pickling Line (CPL) to remove the oxides or scales from the strip surface, thereby enabling further reduction of thickness to the desired level in the Cold Rolling Mill (CRM). This processing is necessary since rust is formed on the surface of the coils at room temperature, whereas scales are formed at a high temperature during rolling in the hot strip mill.

The installed production capacity of the CPL is 3,55,806 million tonnes per annum (MTPA).

Cold Rolling Mill Operations
There are two types of Cold Rolling Mill (CRM) operations - 6 Hi CRM and 4 Hi CRM.

Pickled hot rolled coils of higher gauges are reduced to the necessary thinner gauges by being processed through the mills. In 6 Hi CRM, the reduction achieved is upto 0.13 mm ultra thin guage, whereas 4 Hi CRM can reduce the thickness upto 0.25 mm. The computer-controlled rolling process ensures closure thickness tolerances and perfectly flat strips.

The installed production capacity of the 6 Hi mill is 2,30,856 MT per annum and that of the 4 Hi mill is 43,502 MTPA.

Electrolyic Cleaning Line
The Electrolytic Cleaning Line (ECL) is necessary in case the material is rolled with a high percentage of oil while reduction in the mills. An oil-free base material is essential for the production of bright and corrosion resistant steel. Sodium orthosilicate is used as a cleaning agent in ECL. Tension is given according to thickness and width, based on customer requirements.

The installed production capacity of the line is 86,102 MTPA.

Batch Annealing Furnace
The process of annealing of cold rolled coils is carried out to obtain the desired properties in the finished coils. For this, the material is heated to a pre-determined temperature in a protective atmosphere and soaked for a specified time, before it is cooled to room temperature.

It is necessary to maintain optimum conditions in respect of the annealing atmosphere, annealing cycle, sealing and purging in order to obtain a finished product with a bright surface, the desired micro structure and uniform properties throughout the coil. SD is used for heating the surface. Nitrogen, obtained from the PSA Unit, is purged inside the inner cover.

The installed production capacity of the line is 75,881 MTPA.

Skin Pass Mill
In this process, the cold rolled annealed strips are given the desired surface finish. This improves the flatness and suppresses the yield point elongation. Anti-rust oil is used on the strip surface as protection from rust.

The installed production capacity of the Skin Pass Mill is 82,319 MTPA.

Cold Roll Slitter
In the Cold Roll Slitter, coils are slitted by length and side trims are removed to obtain a uniform width throughout the coil, as per customer requirements.

The installed production capacity of the cold roll slitting line is 96,006 MTPA.

Cut-to-Length Line
In Cut-To-Length Line (CTL), slitted coils are sheared to the desired length as per customer requirements. There are a total of four CTL lines in operation.

The installed production capacity of all CTLs is 83,289 MTPA.

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