The presence of insoluble clay slimes in phosphate ore adversely affect phosphate flotation performance. In this study, the feasibility of using a clay binder as slime depressant for phosphate flotation was investigated by conducting batch mechanical flotation tests using a 16-200 mesh phosphate sample under various operating conditions. The flotation process parameters examined for their impacts on clay binder performance included collector dosage, binder dosage and conditioning time, flotation time, etc. Results have shown that use of 0.1lb/t clay binder increased phosphate yield and recovery by 1.7% and 5.5% respectively with a two min. flotation time. The concentrate grade was essentially constant at about 24%. The highest yield of 16.09% and the highest recovery of 91.01% were obtained with 0.25lb/t clay binder.