Case Study: Hot Metal Ltd

Site details and history

Hot Metal Ltd. is a 35-person heat treatment company situated in the Black Country. The company's site consists of three units: unit 1 houses the heat treatment shop and tool room; unit 2, the metal stores and press shop; and unit three, offices and a small testing lab. Although acquired as a modern industrial facility in 1979, the site has a long industrial history. Prior to 1979, a vehicle repair shop had occupied the site for twenty years, and before that it had been a forge.

The company undertakes a range of batch heat treatment operations including carburising, nitriding, annealing and stress relieving. A small quantity of pressed metal components are also manufactured to customer requirements and heat treated. Work is mainly for the electronic and electrical industry, and the site is a 1^st tier supplier.

Structure of the organisation

A diagram showing the structure of the organisation is given below. (Fig.1).

Personnel

Environmental issues are managed through the Operations Manager who keeps up-to-date with relevant environmental legislation and ensures that environmental duties are carried out. The Lab Technician has responsibility for ensuring that any hazardous materials and wastes are suitably stored to prevent risks to health, safety and the local environment. Responsibility for checking that emergency spill procedures and kits, and for training personnel to deal with spills has been given to the Production Manager. The segregation and disposal of waste is dealt with by the Storeman.

Materials Management

Metal components, contained in the customer's own stillages, are either collected using the company van or delivered to site by customers. A range of different metals and special alloys are bought in standard sized strips from a number of suppliers, and stored in the metal stores until required. Drums of trichloroethylene (trike) are stored on a purpose built sump pallet. The company is considering changing from trike, an ozone depleting substance, to a water based cleaner. This would mean investing in new equipment. Mineral oil is delivered to the site by tanker. A 4,000 litre capacity tank of oil is situated in the rear yard. The tank is as old as the company and stands in a brick built bund, which is about a metre high. There is no sight glass on the tank and the inlet valve overhangs the bund wall. Cradles of hydrogen and ammonia cylinders are kept in a locked cage near the oil tank. A large liquid nitrogen vessel is situated at the front of the site. The vessel is enclosed to prevent damage. Deliveries to the vessel are made by road tanker.

Processes

Strips of metal are fed through the automated presses. The components are punched out of the strips and collected in bins. There are four press machines in the one area and operators have to wear ear defenders at all times that the machines are operational.

The company operates three electric, oil-sealed furnaces. If necessary, components are degreased using trike in a vapour degreaser before they are loaded onto jigs and placed in the furnaces. The furnaces are heated to the required temperature, then gases are introduced into the furnace to produce the correct atmosphere for treatment. Gases are vented to atmosphere via flues. The hydrogen gas is burned off to prevent a build of the gas within the building. When the heat treatment cycle has been completed, components are cooled or first quenched in oil and then cooled.

A circulatory cooling water system is used to cool the furnaces. The cooling water is pumped around furnaces and then pumped to cooling tower installation located in the rear yard. The cooled water is replenished with fresh water and recirculated through the system. In order to descale the water and prevent the growth of Legionella, an automatic chemical dosing plant descaling and biocidal into the cooling system. The dosing plant is operated by external contractors who periodically visit the site and take water samples in order to adjust the dosing rate.

The finished components are inspected and returned to customers in original containers. All rejected and scrap components are returned to customer for disposal. The laboratory is used for testing and analysing production samples. It contains equipment including polishing wheels and hardness testers and a small stock of testing chemicals (mainly solvents and concentrated acids).

Waste

The main wastes produced on site are quench oil and contaminated trike. At present, no arrangements are in place to remove either wastes, and it is stockpiled in the rear yard in a variety of containers. The drums are not marked and there are visible signs of oil contamination in a nearby storm drain. Waste water from the cooling system is disposed of to the foul sewer along with the sewerage from the toilets and washrooms. An 8 cubic yard skip located in the rear yard is used to contain general rubbish from the production units and the offices. The company has an annual contract with a waste contractor, who collects the skip on a weekly basis and disposes the waste to landfill. A separate skip is maintained for scrap steel components and smaller bins are maintained for the alloy metals. All the scrap metal is sold to a local scrap metal merchant who collects the scrap from the site. Empty gas cylinders are returned to the suppliers when the deliver the new cylinders. There are various broken pallets left lying around the yard. These are usually burnt on site.

A copy of all waste contractor's licences are kept on site, however waste transfer notes are incomplete and in some cases, missing.

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