Andrew Carnegie invested in Frick Coke Company because he wanted to invest in a company that could supply coke to his steel companies.
Overall Andrew Carnegie saw the immense potential in the expanding railroads and he wanted to invest in a wide variety of companies that were connected with supplying the growth of the American railway system.
Intially he only bought 11% of the ocmpany in 1880. Within the next 7 years he had bought over 74% of the company.