Refractory lining life enhancement

I am working on a project regarding furnace lining life

The furnace I am working on is a INDUCTION TYPE OPEN CHAMBER FURNACE used for melting of cast iron upto temprature of 1500+/- 100oC.

This time the furnace lining done is of silicates+ sand +clay with binding material as BORIC ACID and it's highest life achieved is 400Hrs.

The content related to Aluminum and Alumina are restricted to be used in furnace lining as it cause impurity to the metal.

I wanna know from u all if u can suggest me something to enhance my refractory life anymore using some chemical or treatment.

If u have any of such ideas contact me on my email id deepansh89u94@yahoo.co.in