An apparatus manually transportable by an operator for spraying an abrasive mixture (M) for removing writings, drawings or graffiti therefrom, towards a delicate surface (S). The apparatus can be used with means (5) for supplying air (G) and second means (7) for supplying water (H) and comprising an inlet port (15) fluidically connectable with the first air inlet means (5), at least one tank (21) for an abrasive powder (A), a first Venturi effect mixing chamber (31) having an outlet (34) for a first air (G) - abrasive powder (A) mixture. The apparatus further comprises at least one spray lance (51) manually operable by the operator, the apparatus comprising a second mixing chamber (55) having a third inlet (56) fluidically connected with the first outlet (34) for the inflow of the air (G) - abrasive powder (A) mixture, a fourth inlet (57) fluidically connectable with the second means (7) for supplying water (H) and an outlet (58) for the abrasive mixture (M) formed by water (H) and by the first air (G) - abrasive powder (A) mixture. The spray lance (51) further comprises at least one outlet nozzle (59) fluidically connected with the outlet (58) of the second mixing chamber (55) to spray the abrasive mixture (M) towards the delicate surface (S). In particular, the second mixing chamber (55) is arranged in the proximity of the outlet nozzle (59) so as to prevent the abrasive mixture (M) from depositing upstream of the second mixing chamber (55).
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