Wet oxidation treatment method of liquid waste containing mineral substances, in which: - a solution charged with oxidizable substances is prepared for being treated, - an oxidizing gas is mixed with said solution, - the mixture solution to be treated and an oxidizing gas are preheated in a first heat exchanger, - said mixture to be treated and oxidizing gas are heated in a reactor at temperatures that are sufficient to oxidize said oxidizable substances, - a division of the flow of the hot treated mixture is carried out at the outlet of said reactor into a first flow fragment and into a second flow fragment, - said first flow fragment of hot treated mixture is used for regulating the preheating temperature of said first heat exchanger, - said first flow fragment is removed after its use in the first heat exchanger, characterised in that: - the second flow fragment of hot treated mixture is cooled in a second heat exchanger, - treatment gases are separated from mineral residues in the second flow fragment of treated mixture at the outlet of said second heat exchanger, - treatment gases are respectively removed from separated mineral residues and the second flow fragment of treated mixture, - the flow rate of the first flow fragment of hot treated mixture is kept constant in said first heat exchanger regardless of the flow rate of the solution to be treated by means of at least one diaphragm arranged after the outlet of said first flow fragment of the first heat exchanger when the said first flow fragment has been used and cooled, and - a double temperature control loop of the said first temperature exchanger is defined by adjusting the flow of the cold solution to be treated at the inlet of said first heat exchanger as a function of the temperature of the hot solution to be treated when it leaves this exchanger and according to the temperature of the reactor, said reactor temperature determining the temperature of the first flow fragment of hot treated mixture prior to its use in said first heat exchanger. - a solution charged with oxidizable substances is prepared for being treated, - an oxidizing gas is mixed with said solution, - the mixture solution to be treated and an oxidizing gas are preheated in a first heat exchanger, - said mixture to be treated and oxidizing gas are heated in a reactor at temperatures that are sufficient to oxidize said oxidizable substances, - a division of the flow of the hot treated mixture is carried out at the outlet of said reactor into a first flow fragment and into a second flow fragment, - said first flow fragment of hot treated mixture is used for regulating the preheating temperature of said first heat exchanger, - said first flow fragment is removed after its use in the first heat exchanger, characterised in that: - the second flow fragment of hot treated mixture is cooled in a second heat exchanger, - treatment gases are separated from mineral residues in the second flow fragment of treated mixture at the outlet of said second heat exchanger, - treatment gases are respectively removed from separated mineral residues and the second flow fragment of treated mixture, - the flow rate of the first flow fragment of hot treated mixture is kept constant in said first heat exchanger regardless of the flow rate of the solution to be treated by means of at least one diaphragm arranged after the outlet of said first flow fragment of the first heat exchanger when the said first flow fragment has been used and cooled, and - a double temperature control loop of the said first temperature exchanger is defined by adjusting the flow of the cold solution to be treated at the inlet of said first heat exchanger as a function of the temperature of the hot solution to be treated when it leaves this exchanger and according to the temperature of the reactor, said reactor temperature determining the temperature of the first flow fragment of hot treated mixture prior to its use in said first heat exchanger. - the second flow fragment of hot treated mixture is cooled in a second heat exchanger, - treatment gases are separated from mineral residues in the second flow fragment of treated mixture at the outlet of said second heat exchanger, - treatment gases are respectively removed from separated mineral residues and the second flow fragment of treated mixture, - the flow rate of the first flow fragment of hot treated mixture is kept constant in said first heat exchanger regardless of the flow rate of the solution to be treated by means of at least one diaphragm arranged after the outlet of said first flow fragment of the first heat exchanger when the said first flow fragment has been used and cooled, and - a double temperature control loop of the said first temperature exchanger is defined by adjusting the flow of the cold solution to be treated at the inlet of said first heat exchanger as a function of the temperature of the hot solution to be treated when it leaves this exchanger and according to the temperature of the reactor, said reactor temperature determining the temperature of the first flow fragment of hot treated mixture prior to its use in said first heat exchanger.