Multi-mineral explorer Petratherm Ltd (ASX:PTR) is set to plug $1.6 million into upcoming drilling work at its Muckanippie Titanium Project in South Australia, following completion of a successful placement. The placement comprised around 45.7 million fully paid ordinary shares priced at $0.035 (or 3.5 cents) each, and it attracted support from both new and existing investors. Petratherm CEO Peter Reid contributed $20,000, while directors of the company collectively have agreed to add $200,000. Petratherm is also looking to bank another $1 million with the offer of a share purchase plan, invit…