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Carbomaster



Carbonising is the process of removing vegetable matter from raw wool, wastes such as noils or card wastes, by acidification (usually with sulphuric acid), baking, mechanical dusting to remove the embrittled cellulose and neutralisation. The process is most important in Australia, Japan, and the Far East and increasingly in South Africa, but less so in Western Europe where there has been a considerable reduction in carbonising plants in the last 5-10 years.

The high fault (i.e. high vegetable-matter content) wools tend to be processed either in the country of origin or near to it. The sulphuric acid process is the typical industry stANDARd process adopted internationally.

Wools with more than 2-3% VM are usually carbonised, wools with less than this can be sent to the cards and combs directly from scouring, and the cards and combs will remove the VM.

Carbonising Process In Brief

The raw wool is first scoured to remove any grease and dirt to enable the acidifying process to be more effective. The wet out wool is then soaked in an acid solution of 6-7% w//v along with a trace dose of non-ionic surfactant where the wool and vegetable matter absorb the acid, commencing the carbonising process.

Following the Acid Bowls the wool is either double squeezed or continuous centrifuged (Roussellet) to reduce the acid content of the wool prior to the dryer to protect the fibre from acid damage. The wool is then dried in a specialist drum dryer operating at low temperatures (70-80 degrees Celsius) and high airflows, drying down to a low regain of 4-6%.

The process is slow since sufficient time must elapse for the vegetable matter to react preferentially with the sulphuric acid and for the subsequent baking to embrittle the acidified cellulose.

The wool is then conveyed on to the ANDAR continuous Conveyor Dryer where the wool is baked at 110 - 120 degrees Celsius for ten minutes, causing the vegetable matter to turn to carbon.

Following the baking process the wool passes through multiple sets of crushing rollers where the embrittled vegetable matter is passed between fluted rollers which crush the VM allowing it to be separated from the wool. Following each crusher is a 5 drum Stepped Opener Duster to remove the charred vegetable matter dust. Generally there will be four sets of Burr Crushers integrated with 5 drum Stepped Opener Dusters.

The wool, now largely free from vegetable matter, contains a small residual dust volume and is highly acidic, so needs to be washed and neutralised. The neutralising line consists of up to 5 Bowls where it is neutralised with sodium carbonate, rinsing and bleaching processes to complete the carbonising process.

Finally the carbonised wool is dried within a drum dryer to customer specified regain prior to pressing and packaging for transport.
Wetting Bowl
A traditional short Scouring Bowl designed to simply wet out the wool prior to the acid bowl.
Squeeze Press
The ANDAR Squeeze Press minimises carry over between bowls providing isolation of specific application bowls.
Acid Bowl
A specialist Acid Applicator Bowl, constructed from corrosion resistant materials to withstand the demanding requirements of this application.
Acid Squeeze Press
The ANDAR Squeeze Press minimises carry over between bowls providing isolation of specific application bowls. This Squeeze Press is paired with the Acid Bowl and is designed to handle the high corrosive demands in this application.
Drying
A specialist 6 Drum Dryer is used to dry the acid soaked loose stock to less than 10% regain at low temperature. The Dryer is built with acid protection for the first two drums. The Dryers exhaust system is built to cater for the high acid content exhaust discharge.
Baking
The ANDAR Drum Dryer is used for the first baking phase to bake the loose stock at 110 -130 ºC. This bakes the easily dried VM (with the higher acid concentration) turning it to carbon, while the wool remains intact.
Crushing and Dusting
The wool is passed between fluted rollers, which crush the brittle carbonised VM. Dusters then beat the crushed dust out of the wool, which is now clean, very dry and very acidic.
Scoured Feed Hopper
The use of a scoured wool feeder following both the specialist Drum Dryer and the Stepped Opener Dusters allows for the wool mat to be evenly spread across the full working width of the Burr Crushers providing a uniform feed and a thinner mat that is more easily crushed.
Burr Crusher
The Burr Crusher consists of 4 pairs of fluted rollers which transport the wool and crush the vegetable matter. The dust produced in the Burr Crusher is automatically sucked away.
Stepped Opener Duster
This process is the preferred system for carbonising de-dusting duties. The wool exits the Burr Crushers and is fed onto the infeed conveyor / nip roller assembly. The ability to vary the speed of the infeed and drums allows the operator to vary the amount of opening / dusting. The nip roller retards the wool flow while the drums dust the wool. Waste is removed pneumatically and is conveyed to a cyclone.
Baking
The ANDAR Conveyor Dryer is used to bake the loose stock at 110 -130 ºC for ten minutes. This bakes the harder VM (with the higher acid concentration) turning it to carbon, while the wool remains intact.
Crushing and Dusting
The Burr Crusher consists of 4 pairs of fluted rollers, which transport the wool and crush the vegetable matter. The dust produced in the Burr Crusher is automatically sucked away.
Neutralising Line
The Neutralising Line restores the pH levels of the highly acidic loose stock fibre, through a series of warm rinsing, soda ash addition and bleaching bowls. The Neutralising line serves a dual purpose and also removes any residual dust from the crushing and dusting phases.
Final Dryer
The final stANDARd 6 Drum Dryer dries the loose stock, now free from VM contaminants, to the customers specified regain ready to be packaged or sent to the top making mill.

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