The problem of tuyere refractory wear has been studied in an air-water model. Erosion tests, with boric acid (H₃BO₃) disks as refractory simulators, and measurements of back-attack frequency were carried out. The erosion pattern showed two distinct features: isolated elliptical pits and a continuous irregular shear wear pattern. The influence of surface hardness and gas flow rate was investigated. Pitting was found most frequently on disks formed at the lowest pressure (10 tons), but for pressures greater than 20 tons, little difference was seen between disks. When the gas flow was in the bubbling regime, pitting was observed inside the region closest to the tuyere tip, with a maximum at the transition to jetting flow. Occasionally, pits could still be observed when the gas flow rate was rather high (NMa = 1.82). The irregular wear pattern appeared independent of disk surface properties, however sensitive to the gas flow rate. In the bubble flow regime, wear was seen only outside a certain radius, which corresponds to the radius of the bubbles. In the jetting regime, wear was also observed close to the tuyere. The disk weight loss showed a maximum in the bubbling-to-jetting transition region, where the back-attack frequency also reach a maximum. The results support the idea that cavitation erosion, through liquid microjet pitting, is the main mechanical wear agent. A model for the generation and collapse of cavitation bubbles is proposed. Applied to gas injection into liquid metals, the model suggests greater erosion due to higher cavitation intensity, but also indicates ways of reducing cavitation erosion of tuyere refractory.