...Compania de Minas Buenaventura S.A.A.'s investment-grade rating reflects the company's low-cost mining operations, diversified portfolio of base and precious metals, strong capital structure and robust credit metrics. Further factored into the rating is Fitch Ratings' expectation that the company will retain adequate liquidity levels and low refinancing risk while the company undertakes a series of brownfield and greenfield projects to grow and maintain its operations....