NOVELTY - Hydrothermal carbonization of biomass in a deep shaft reactor comprises: providing a flowable starting mixture, which comprises biomass suspended in water and optionally comprising at least one catalysts (3); supplying the starting mixture to a deep shaft reactor; and maintaining the downstream reducing conditions, in which the hydrothermal carbonization of the starting mixture in the descending allows biomass to form particulate carbon-rich compounds, where upstream resultant reaction mixture is added with oxygen-containing fluid.    USE - The method is useful for hydrothermal carbonization of biomass in a deep shaft reactor.    ADVANTAGE - The method allows good handling and results in less polluted water reaction.    DETAILED DESCRIPTION - Hydrothermal carbonization of biomass in a deep shaft reactor comprises: providing a flowable starting mixture, which comprises biomass suspended in water and optionally comprising at least one catalysts (3); supplying the starting mixture to a deep shaft reactor; and maintaining the downstream reducing conditions, in which the hydrothermal carbonization of the starting mixture in the descending allows biomass to form particulate carbon-rich compounds, where upstream resultant reaction mixture is added with oxygen-containing fluid, such that dissolved organic compounds in ascending reaction mixture are implemented by wet oxidation. An INDEPENDENT CLAIM is also included for a deep shaft reactor to perform a method comprising a leader in a depth of the reaction vessel for the downstream, which is down-comer, where the down-comer is designed such that the down-comer is fed with starting mixture and can be conducted in the downstream into the deep; and the reaction vessel has fluid-conducting leader connected upwards with the down comer for the upward flow, which is up-comer, where the up-comer is designed such that it can be conducted according to the down-comer in the depths of escaping reaction mixture in the up-comer transferable and the upstream, where the deep shaft reactor has a device for introducing the oxygen-containing fluid into the upstream in the up-comer.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a deep-shaft reactor to perform the method.    Biological treatment (2)    Catalyst (3)    Entry (6)    Pump (7)    Suspension (8)