A method for precipitating metal waste as metal borates, wherein the waste which contains dissolved metal salts, is mixed with a boron compound, and the pH is adjusted to a value at which precipitation takes place in the presence of precipitation nuclei necessary for the formation of metal borates, wherein the pH is adjusted to increase gradually, for precipitating two or more metals contained in the waste as borates, characterized by - providing precipitation nuclei formed in another precipitation reaction by selecting and carrying out option 1) or 2): 1) first precipitating a first metal into metal hydroxide at a first pH to form precipitation nuclei, which takes place at a lower pH than the hydroxide precipitation of a second metal, if the metals to be precipitated into borates include a metal suitable for forming the precipitation nuclei, and - using the precipitation nuclei for precipitating the second metal as a borate at a higher second pH, and using the second metal borate as precipitation nuclei for precipitating at least the first metal as a borate, or - 2) if the metals to be precipitated into borates do not include any metals suitable for forming the precipitation nuclei according to option 1), adding a metal borate of a metal at a first pH to act as precipitation nuclei, and - using the precipitation nuclei for precipitating at least a first metal as a borate at a higher second pH, and using the first metal borate as precipitation nuclei for precipitating at least a second metal as a borate. - providing precipitation nuclei formed in another precipitation reaction by selecting and carrying out option 1) or 2): 1) first precipitating a first metal into metal hydroxide at a first pH to form precipitation nuclei, which takes place at a lower pH than the hydroxide precipitation of a second metal, if the metals to be precipitated into borates include a metal suitable for forming the precipitation nuclei, and - using the precipitation nuclei for precipitating the second metal as a borate at a higher second pH, and using the second metal borate as precipitation nuclei for precipitating at least the first metal as a borate, or - 2) if the metals to be precipitated into borates do not include any metals suitable for forming the precipitation nuclei according to option 1), adding a metal borate of a metal at a first pH to act as precipitation nuclei, and - using the precipitation nuclei for precipitating at least a first metal as a borate at a higher second pH, and using the first metal borate as precipitation nuclei for precipitating at least a second metal as a borate. 1) first precipitating a first metal into metal hydroxide at a first pH to form precipitation nuclei, which takes place at a lower pH than the hydroxide precipitation of a second metal, if the metals to be precipitated into borates include a metal suitable for forming the precipitation nuclei, and - using the precipitation nuclei for precipitating the second metal as a borate at a higher second pH, and using the second metal borate as precipitation nuclei for precipitating at least the first metal as a borate, or - 2) if the metals to be precipitated into borates do not include any metals suitable for forming the precipitation nuclei according to option 1), adding a metal borate of a metal at a first pH to act as precipitation nuclei, and - using the precipitation nuclei for precipitating at least a first metal as a borate at a higher second pH, and using the first metal borate as precipitation nuclei for precipitating at least a second metal as a borate. - using the precipitation nuclei for precipitating the second metal as a borate at a higher second pH, and using the second metal borate as precipitation nuclei for precipitating at least the first metal as a borate, or - 2) if the metals to be precipitated into borates do not include any metals suitable for forming the precipitation nuclei according to option 1), adding a metal borate of a metal at a first pH to act as precipitation nuclei, and - using the precipitation nuclei for precipitating at least a first metal as a borate at a higher second pH, and using the first metal borate as precipitation nuclei for precipitating at least a second metal as a borate.