[en] The paper considers the problem of predicting the quality of metallurgical production in a general formulation, when a huge amount of historical data of technological processes and product quality can be partitioned into a set of discrete classes of efficiency. Assuming that in the production process the technological process route can be changed, the problem of choosing the optimal route becomes important. When constructing the decision tree that recognizes the class of efficiency of the technological process, a special criterion for optimality of the partitioning of the set of classes of efficiency into two classes is introduced corresponding to the left and right branches of the decision tree in the node under consideration. The partitioning obtained by the proposed approach is close to optimal and can form the basis for constructing a decision tree, with the help of which a route is chosen to continue processing. (paper)