Trouble broke out when the contractual teachers of about 165 schools run by ECL went to the company's headquarters office, 20 km from Asansol to submit their nine-point charter of demands this morning.
The demands included hike in salary and pension after 60 years of age.
They were stopped at the gates by security guards for not having prior appointment which led to a scuffle between the two sides.
Police said it was called in at this point by the ECL authorities.
The police, however, denied having made the baton charge and said it only pushed back the demonstrators and detained the eight.