Method for treating raw brines from desalination plants having a total salt content of more than 60 g/l the method comprising the following steps in the following sequence: a) conveying a magnesium ion-containing solution having a magnesium ion content of more than 1 g/l, in particular raw brines from seawater desalination plants having a total salt content of more than 60 g/l, through a first vertical column containing a bed filling of zeolite A at a temperature of between 75 °C and 100 °C in a flow direction from top to bottom, the zeolite A being converted to thermally modified zeolite in the process; b) cooling the interior of the first column filled with the bed of TMZ to a temperature of below 45 °C; c) conveying a sodium ion-containing solution having a sodium ion concentration of more than 50 g/l and a temperature of below 45 °C through the bed of TMZ in the first column in a flow direction from bottom to top; d) conveying the raw brine to be treated through the first column filled with the bed of TMZ at a temperature of from 30 °C to 45 °C in a flow direction from top to bottom until the calcium ion concentration of the eluate exiting the first column surpasses a value of 1,000/n mg/l, indicating that calcium ions have broken through the bed of TMZ, wherein n is the factor of concentration increase of the eluate in the next step e); e) separating the eluate of step d) in a desalination device into water that has a total salt content of less than 500 mg/l and into a more highly concentrated brine that has a calcium ion concentration of less than 1,000 mg/l, wherein the concentration of the more highly concentrated brine relative to the eluate of step d) increases by the factor n; f) conveying the concentrated brine of step e) through the bed of TMZ in the first column at a temperature of below 45 °C in a flow direction from bottom to top; g) separating the concentrated eluate of method step f) into solids and water in a solids unit; h) repeating steps d) to g) until the capacity of the TMZ is exhausted, exhaustion of the TMZ being identified by the eluate in step d), immediately after conversion of the TMZ into sodium form by step f), already having a calcium ion concentration in the first bed volume conveyed through the first column that, under otherwise identical conditions, is 20 % higher than the calcium ion concentration in the first bed volume conveyed through the first column in step d) immediately after performing steps a) to c). a) conveying a magnesium ion-containing solution having a magnesium ion content of more than 1 g/l, in particular raw brines from seawater desalination plants having a total salt content of more than 60 g/l, through a first vertical column containing a bed filling of zeolite A at a temperature of between 75 °C and 100 °C in a flow direction from top to bottom, the zeolite A being converted to thermally modified zeolite in the process; b) cooling the interior of the first column filled with the bed of TMZ to a temperature of below 45 °C; c) conveying a sodium ion-containing solution having a sodium ion concentration of more than 50 g/l and a temperature of below 45 °C through the bed of TMZ in the first column in a flow direction from bottom to top; d) conveying the raw brine to be treated through the first column filled with the bed of TMZ at a temperature of from 30 °C to 45 °C in a flow direction from top to bottom until the calcium ion concentration of the eluate exiting the first column surpasses a value of 1,000/n mg/l, indicating that calcium ions have broken through the bed of TMZ, wherein n is the factor of concentration increase of the eluate in the next step e); e) separating the eluate of step d) in a desalination device into water that has a total salt content of less than 500 mg/l and into a more highly concentrated brine that has a calcium ion concentration of less than 1,000 mg/l, wherein the concentration of the more highly concentrated brine relative to the eluate of step d) increases by the factor n; f) conveying the concentrated brine of step e) through the bed of TMZ in the first column at a temperature of below 45 °C in a flow direction from bottom to top; g) separating the concentrated eluate of method step f) into solids and water in a solids unit; h) repeating steps d) to g) until the capacity of the TMZ is exhausted, exhaustion of the TMZ being identified by the eluate in step d), immediately after conversion of the TMZ into sodium form by step f), already having a calcium ion concentration in the first bed volume conveyed through the first column that, under otherwise identical conditions, is 20 % higher than the calcium ion concentration in the first bed volume conveyed through the first column in step d) immediately after performing steps a) to c).