Deposition of carbon particles on plastic spheres was experimentally investigated. The effects of CaCl2 concentration, so ap concentration and the mixing speed on the deposition rate and the equilibrium particle concentration were studied. The effect of the above parameters on the Langmuir model constants was also determined. In the absence of CaCl2, almost no deposition takes place. However, when CaCl2 was added, the deposition becomes very fast. A large equilibrium constant was obtained when the concentration of CaCl2 equals the stoichiometric amount necessary to react with the sodium stearate soap. On the other hand, when the concentration of CaCl2 was above the stoichiometric amount, both coagulation of carbon particles and deposition took place simultaneously. When the soap concentration was above the stoichiometric amount the deposition rate is slow. Further increase in the soap concentration has similar effect on the deposition rate. The effect of mixing speed on the deposition rate was examined. Mixing speeds of 100, 300 and 500 rpm were used. Results showed that the deposition rate increases as the mixing speed increases until a certain point is reached where it starts to decrease.