About Carbon Electrode Paste

Carbon Electrode Paste is a self-baking electrode used in submerged arc furnaces for delivering power to the charge mix. Electrode Paste is added to the top of the electrode column in either cylindrical or briquette form. As the paste moves down the electrode column the temperature increase causes the paste to melt and subsequently bake forming a block of electrically conductive carbon. Electrode Paste is essentially a mix of Electrically Calcined Anthracite (ECA) or Calcined Petroleum Coke (CPC) with Coal Tar Pitch.

Manufacturing Process

CPC received from our Barauni plant or ECA received from our overseas suppliers is screened to different fractions and stored in hoppers. The various fractions are then weighed using a batching system and taken in a bin. The composition of fractions is taken according to the desired Electrode Paste properties. The resulting aggregate is preheated in a mixer to temperatures up to 180oC and Coal Tar Pitch at 200oC is then added and mixed. The quantity of Coal Tar Pitch added varies depending on desired plasticity. Coal Tar Pitch which is used as a binder in the product is manufactured in-house, using Crude Coal Tar from different sources so as to get the precise Electrode Paste quality.

SPECIFICATIONS OF CARBON ELECTRODE PASTE

GREEN PASTE

Property Unit ECA Based CPC Based
a) Plasticity % As per customer's requirement, typical range 30-35 As per customers requirement, typical range 30-35
b) Fixed Carbon % 83 Min 87 Min
c) Volatile Matter % 11 - 12 12 - 13
d) Ash % 5.0 Max 0.5 Max
e) Apparent Density gm/cc 1.68 Min 1.68 Min

BAKED PASTE

Property Unit ECA Based CPC Based
a) Fixed Carbon % 94 Min 99 Min
b) Porosity % 25 Max 35 Max
c) Apparent Density gm/cc 1.45 Min 1.40 Min
d) Cold Crushing Strength kg/cm2 250 Min 200 Min
e) Electrical Resistivity Ohm.mm2 / meter 55 to 65 85 to 95

Note : Plasticity can be altered to suit the customerís requirement. We can supply Electrode Paste in both cylinders and briquettes or as per customerís requirement though the most preferred size is 2 Ė 4 inch briquettes. CR recommends using ECA based electrode paste for enhanced furnace performance.