*Article* **A Case Study of Rock Type Prediction Using Random Forests: Erdenet Copper Mine, Mongolia**

**Narmandakh Sarantsatsral <sup>1</sup> , Rajive Ganguli 1,\* , Rambabu Pothina <sup>1</sup> and Batmunkh Tumen-Ayush <sup>2</sup>**

<sup>1</sup> Department of Mining Engineering, University of Utah, Salt Lake City, UT 84112, USA;

n.sarantsatsral@utah.edu (N.S.); rambabu.pothina@utah.edu (R.P.)

<sup>2</sup> Erdenet Mining Corporation, Erdenet 61027, Mongolia; tbatmunkh@erdenetmc.mn

**\*** Correspondence: rajive.ganguli@utah.edu

**Abstract:** In a mine, knowledge of rock types is often desired as they are important indicators of grade, mineral processing complications, or geotechnical attributes. It is common to model the rock types with visual graphics tools using geologist-generated rock type information in exploration drillhole databases. Instead of this manual approach, this paper used random forest (RF), a machine learning (ML) algorithm, to model the rock type at Erdenet Copper Mine, Mongolia. Exploration drillhole data was used to develop the RF models and predict the rock type based on the coordinates of locations. Data selection and model evaluation methods were designed to ensure applicability for real life scenarios. In the scenario where rock type is predicted close to locations where information is available (such as in blocks being blasted), RF did very well with an overall success rate (OSR) of 89%. In the scenario where rock type was predicted for two future benches (i.e., 30 m below known locations), the best OSR was 86%. When an exploration program was simulated, performance was poor with a OSR of 59%. The results indicate that EMC can leverage RF models for short-term and long-term planning by predicting rock types within drilling blocks or future blocks quite accurately.

**Keywords:** machine learning; random forest; rock type; mining geology
