In a study to investigate how the degree of grinding influenced the concentration of celestite, the concentrate was found to increase in celestite (SrSO4) content from 52 to 65 mass% when the size was reduced from 80/100 (177/149) to 160/200 mesh (88/74 mum). Experiments were conducted for the concentration of celestite ore by flotation using a mechanical cell with a 3 1 capacity for particles sizes ranging between 80 and <400 mesh (177 and <37 mum), and modifying both pH in the flotation cell and collector (sodium oleate) concentration. The results obtained show that, although recovery percentages are low, celestite content in the concentrate is approximately 70 mass%.