Using the example of a selected part of one lignite deposit, this study analyzes the problem of quality control of the mined lignite stream at the stage of operational planning. A single quality parameter of the deposit was selected for analysis - the calorific value of raw lignite Qr. Based on the drill holes from the exploitation phase, models of spatial variability for this parameter were created. The models were built using two geostatistical methods - ordinary block kriging and sequential Gauss conditional simulation. The modeling was done in blocks which correspond with the size of daily production. Advantages and disadvantages of the modeling methods were outlined together with their suitability for use in controlling raw material quality. Based on the direction of mining of particular exploitation blocks, the variability of the calorific value over a 6-month period was analyzed. The conditional simulation allowed for the creation of maps of the probability of exceeding certain upper and lower thresholds of the calorific value. The summary of the article proposes a method of mitigating the cyclical changes in the calorific value. The concept is to blend lignite of different quality in order to obtain a relatively stable value.