Companion Building Materials (Holdings) plans to raise $19.4 million by placing two sets of warrants with institutional and private investors. Proceeds of the issues, which need shareholders' approval, will cut the company's debt by $10 million and provide funds to expand production capacity in China. Companion, which recently spun off Companion Marble, distributes ceramic tiles and granite and marble products. The first warrants to be issued, at 35 cents each, will entitle holders to buy Companion shares at $1.10 each by September next year and will give them another free warrant. The second issue, which will expire in September 1998 and is priced at 38 cents, will entitle holders to buy shares at $1.25 each.