Platinum alloy catalyst gauzes have been primarily used since the early 1900s for the oxidation of ammonia to nitric oxide for the industrial manufacture of nitric acid, caprolactam, hydrogen cyanide, sodium nitrite, etc. A mixture of ammonia and air/ oxygen is passed through platinum alloy catalyst gauzes (at specified temperature and pressure) for the conversion to nitric oxide.
Hindustan Platinum (HP) started manufacturing of platinum alloy woven catalyst gauzes in 1963. Since 1994, HP has been designing and manufacturing a wide portfolio of ‘Knitted’ catalyst gauzes.
With the use of flat-bed knitting technology, we are able to provide a smart portfolio of single and multi-structural catalyst gauzes.
In contrast to the conventional mass production of standard gauzes, our technology allows to manufacture each catalyst gauzes individually and in any desired modification such as knitting design, diameter of gauzes and wire, density and alloy composition. As a result, the setup of a catalyst pack for a specific reactor (various configurations specifically designed for each plant depending on its operating parameters) can easily be changed when necessary and can be manufactured within a very short time. HP has the flexibility to offer a wide portfolio of single and multi-structural gauze types that can be truly customized for every plant.
During the operation of a plant, platinum and rhodium from the catalyst is lost due to the volatile oxide formation and also simply by mechanical attrition. A catchment system consisting of palladium alloy gauzes is used for the recovery of such precious metal losses. Due to the tremendous cost of platinum and rhodium compared to the price of palladium, palladium alloy catchment gauzes have been widely used for the recovery of platinum since their introduction in the late 1960s.
With improved technology, catchment gauzes now typically contain 95% palladium and we can recover ~70-85% platinum of the burn off from the catalyst gauzes, depending on the specific operating parameters. HP provides customized plant specific catchment systems, including corrugated catchment packs for high pressure reactors.
Continuous development in ammonia oxidation catalyst-catchment systems have led to the natural progression towards an ‘integrated system’. Depending on the plant design, feasibility and applicability, we also supply plant-specific integrated catalyst-catchment systems that provide significant economic and technical benefit to the customers. Some of these benefits include longer campaign life, reduced precious metal loading, lower net precious metal losses over the campaign period, etc., thereby returning a better value on the investment.
We also make silver gauzes for the manufacture of acetic acid. These gauzes having a wire diameter of 0.35 mm and a wire mesh of 20 per linear inch are woven to width as per specifications provided by the plant designer. The purity of silver used for the manufacture of the gauzes is greater than 99.9%.
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Two types of plant cleaning services are offered by Hindustan Platinum (HP).
Precious metal that escape from the catalyst/ catchment systems over a period of time get deposited on heat exchange surfaces of various down-stream equipments. Destructive cleaning is a process to recover deposited precious metals from the equipments after their useful life.
Since 1997, HP has been carrying out destructive cleaning of plant equipments to recover precious metals. We maximize the recovery of precious metals from redundant equipments by using superior cleaning technology thereby offering the best value to our customers.
Non-destructive cleaning is a process to recover precious metals by chemical and/ or mechanical methods without affecting the residual life of the equipment.
During the normal operation of nitric acid/ caprolactam/ cyanide/ sodium nitrite plants, precious metal escape from the catalyst/ catchment systems, get deposited on the downstream equipments such as tubes of waste heat boiler, economizer, tail gas heater, etc. This lowers the heat transfer across the exchangers and affects plant efficiency.
The essence of clean down operation lies in the mechanical or chemical treatment of the surface, so that maximum precious metal deposits on the exchangers can be removed and collected without affecting the life of the equipments. Non-destructive cleaning has dual benefits to customers,
• Improve efficiency of heat exchangers
• Derive maximum value from recovered precious metals
Hence, it is advisable to periodically clean the plant by the non-destructive method.
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