【Purposes】 In ladle metallurgy, block or whole bag alloy materials and lime are usually added. In recent years, some companies have reported a new process of adding scrap steel to ladle refining furnace. Studying the melting and homogenization mechanism of the above solid substances in the ladle refining process can optimize the refining process and accelerate production rate. 【Methods】 Ice sample and ice sphere made by KCl solution were used in the water model experiment separately to study the mechanisms of motion, melting, and mixing of alloy in a 260 t ladle. These two samples were selected to simulate the light and heavy alloys respectively. The effects of factors such as temperature, bottom blowing flow rate, liquid level height, and addition position on the mechanicms were studied. 【Findings】 The results show that the melting time of both two ice samples decreases dramatically with increasing temperature. The melting process of light ice sample (ice sphere) can be obviously accelerated by increasing the gas flowrate. When the liquid level is high, i.e. the ratio of liquid level to the diameter is 1.1, the melting time of ice sphere is relative short. The melting of ice sphere can hardly be affected by its adding position. For the heavy ice sample (salt sphere), when added from a position which is far away from the nozzle, it stays at the bottom of the ladle and melts slowly. When the salt sphere is added above the nozzle, the chances of washing by the bubbles from plume area increase and the melting time is shortened. Increasing the gas flow rate can reduce the melting time of the salt sphere, and the liquid level has a negligible effect. When the salt sphere is scoured by the bubbles in plume area, the melting time and mixing time are shortened.