An apparatus manually transportable by an operator for spraying an abrasive mixture towards a delicate surface for the removal of writings, drawings or graffiti therefrom, the apparatus being usable with first means for supplying air at a maximum pressure of 8 bars and with second means for supplying water at a maximum pressure of 4 bars, the apparatus comprising: - an inlet port fluidically connectable with the first means for supplying air; - at least one tank for an abrasive powder; - at least one first Venturi effect mixing chamber having a first inlet fluidically connectable with said inlet port, a second inlet fluidically connected with said at least one tank and a first outlet for a first air - abrasive powder mixture; - at least one spray lance manually operable by the operator comprising: - at least one second mixing chamber having a third inlet fluidically connected with said at least one first outlet for the inflow of said first air - abrasive powder mixture, a fourth inlet fluidically connectable with second means for supplying water and a second outlet for the abrasive mixture formed by water and by the first air - abrasive powder mixture; - at least one outlet nozzle fluidically connected with said at least one second outlet of said at least one second mixing chamber to spray the abrasive mixture towards the delicate surface; wherein said at least one second mixing chamber is arranged in the proximity of said at least one outlet nozzle so as to prevent the abrasive mixture from depositing upstream of said second mixing chamber; wherein said tank contains a predetermined amount of said abrasive powder, the apparatus further comprising pneumatic anti-packing means acting on said abrasive powder to facilitate the outflow thereof towards said second inlet, said pneumatic anti- packing means being fluidically connected with said inlet port so that, during use, the air flowing into the apparatus feeds both said at least one spray lance and said anti- packing means; characterized in that said tank includes an upper portion that comprises at least one duct for loading the abrasive powder, the latter including a closing element, the apparatus further comprising pneumatic means for pressurising said tank that include a third duct for the fluidic connection of the upper portion (22 ') of the tank and of said inlet port, so that, during use, the inflowing air, which feeds both said at least one spray lance and said anti-packing means, pneumatically forces the closure of the closing element of said loading duct. - an inlet port fluidically connectable with the first means for supplying air; - at least one tank for an abrasive powder; - at least one first Venturi effect mixing chamber having a first inlet fluidically connectable with said inlet port, a second inlet fluidically connected with said at least one tank and a first outlet for a first air - abrasive powder mixture; - at least one spray lance manually operable by the operator comprising: - at least one second mixing chamber having a third inlet fluidically connected with said at least one first outlet for the inflow of said first air - abrasive powder mixture, a fourth inlet fluidically connectable with second means for supplying water and a second outlet for the abrasive mixture formed by water and by the first air - abrasive powder mixture; - at least one outlet nozzle fluidically connected with said at least one second outlet of said at least one second mixing chamber to spray the abrasive mixture towards the delicate surface; - at least one second mixing chamber having a third inlet fluidically connected with said at least one first outlet for the inflow of said first air - abrasive powder mixture, a fourth inlet fluidically connectable with second means for supplying water and a second outlet for the abrasive mixture formed by water and by the first air - abrasive powder mixture; - at least one outlet nozzle fluidically connected with said at least one second outlet of said at least one second mixing chamber to spray the abrasive mixture towards the delicate surface;