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Eliminating Hazardous Products: Material Savings by Reducing Over Spraying

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A Family-Run Tannery near Bangkok / Thailand

In brief

On a daily basis, this tannery processed about 20 tons of raw hides. Up to 40% of the paints used in the finishing processes were lost due to over-spraying. These materials are costly to buy and the waste is expensive to treat as it is classified as hazardous and must be disposed of in authorised secure landfills that are particularly protected against leakage into soil and ground water. Disposal costs for hazardous waste are more than 4’000 Baht (R 100) per ton. There is an acute shortage of landfill sites for hazardous wastes in the region where Thailand’s tannery clusters are located, which has pushed up disposal costs.

The challenge

The efficiency of sensors used in spraying operations deteriorates over the lifetime of the sensor. In this tannery, sensors were only replaced on a periodic basis. Replacement was often delayed as sensors were not regularly ordered and kept in stock. In the meantime, losses from over-spraying were quite significant, representing monthly losses of about 12’000 Baht (the equivalent of R 300).

Actions taken within the enterprise (after application of the PREMA GHK guide)

As a first step, all sensors in the spraying area were checked. Sensors that were faulty or burned out were replaced with new sensors.

Workers were trained to better place the leather pieces on the conveyer belt to ensure an optimal exposure of the crust during spraying.

Special nozzles were installed on sprayers that produced higher pressure, which resulted in a better distribution of paints onto the crust and the possibility to use a smaller volume of these materials to cover the same area.

The formulation of colours was checked to evaluate possibilities to achieve a higher efficiency during spraying (chemical suppliers can often provide improved recipes/processes for finishing operations).

Environmental benefits

Through a more efficient spraying process, the generation of hazardous waste was reduced substantially. Additionally it led to a reduction of air pollution in finishing processes and to a reduction of waste that required safe disposal.

Economic benefits

Investment cost

19,600 Baht
(R 490)

For the purchase of:

2 replacement sensors
(R 200 each)

6 special nozzles
(R 15 each)

Running costs

40’000 Baht
(R 1,000)

For the cost of:

  • · 5 sensors throughout the course
    of the year

Annual savings

72,000 Baht
(R1,800)

 

Resulting from a reduction of
over-spraying by 50%

 

Payback period

 

Less than 15 months

 

Organizational improvements

This tannery decided to take a more systematic approach to maintenance on an overall basis. Rather than waiting for employees to report break-downs or problems, regular checks were carried out to identify equipment that needed repairs and parts that needed to be replaced. Moreover, the Finishing Department supervisor ensured that sensors were checked at the end of each working day. The head of the material store created a policy to have one replacement sensor continuously available in stock in order to avoid any delays in replacing faulty or burned out sensors.

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