APPLICATION PROCEDURE FOR CHEMICALLY BONDED CASTABLES
APPLICATION PROCEDURE FOR CHEMICALLY BONDED CASTABLES (Phoscast Range):-
These are two component systems consisting of dry powder and a liquid binder, supplied separately. The two components should be mixed together along with a small quantity of water until an adequately “plastic” mass is achieved : Care must be taken while mixing and installation to achieve proper results.
Recommended Proportions:-
1.) Phoscast 60 :
The Phoscast plastic refractory is supplied in two components system i.e. the dry powder mix and the liquid binder (phosphoric acid). The dry powder packing is of 50 kg each, which is to be mixed with 9.25% by weight of dry powder (i.e. 4.6 Kg OR 2800 ml). Water percentage for Phoscast-60 is approx. 4% (2000 ml approx.) by weight of dry powder, which may vary by about 0.25 to 0.5% depending on ambient temp.
2.) Phoscast 90 :
The Phoscast plastic refractories is supplied in two components system i.e. the dry powder mix and the liquid binder (phosphoric acid). The dry powder packing is of 50 kg each which is to be mixed with 9.5% by weight of dry powder (i.e. 4.75 Kg OR 2850 ml). Water percentage for Phoscast-90 XR is 3.5% (1750 ml approx.) by weight of dry powder, which may vary by about 0.25 to 0.5% depending on ambient temp.
Curing & Heating:-
Phoscast refractory hardens adequately after about 24 to 48 hrs in ambient and then progressively develops strength on heang at elevated temperatures. The following curing schedule is recommended for Phoscast plastic refractory. Air Drying minimum 24 hours.
Ambient to 150°C @35-40°C per hour : 4 to 5 hours.
Hold at 150°C : 6-8 hours.
150°C to 350°C @ 40°C per hour : 4 to 5 hours.
Hold at 350°C : 6-8 hours
Gradual Cooling (ambient) to be done in case lining is to be inspected, otherwise the equipment may be taken to operang temperature.
Drying and Heating is essential for essential for Phoscast Refractory, as this is a heat setting refractory.
Equipment :
1. A mechanical paddle mixer having a capacity of about 100 kgs.
2. Wooden wallets (3” dia x 5” length x 10” length) protective rubber gloves (acid proof) mask etc.
3. Graduated container for water / binder measurement.
Mixing:-
The dry powder is discharged into the mixer and dry mixed for two to three minutes. Then the measured quantity of liquid binder is added gradually while the mixing is on. Thereafter, the required water quantity is added and the mass mixed thoroughly until a homogenous plastic mass is obtained. This mass, when pressed with hand or moulded should take the required shape.
The mass should then be covered with a polythene sheet and left for ageing for about 30 minutes, before it is ready for use. It may then be applied over the next 45 minutes.
Note : For testing of the plasticity of the material, make a ball the in the palm of the hand and drop it from 6 to 7 . on to the floor. If it does not break and only flattens, then the mix is acceptable.
Application:-
Phoscast can be applied by ramming with a wooden wallet. The desired lining thickness is built up over several courses, to a uniform thickness. Phoscast should never be troweled to obtain a smooth surface and the surface should be finished by ramming only. Any excess should be sliced off with the edge of a blade (or trowel) and then finished by ramming again.
Venting holes:-
Venting holes may be provided to allow drainage by water from within Phoscast lining as the temperature rises. These are 3-4 mm dia holes, driven at 100-150 mm all over the surface to a depth of approx 2/3 of the thickness of lining. Venting holes need not be distributed regularly.
