Underground mining visible light communications (UM-VLC) is a prospective solution to improve the well-being of workers by having a constant flux of information with them. However, the conditions inside underground mines present critical divergences to indoor environments. These differences exist due to the irregularity of the walls, the scattering produced by heavy dust particles, and the user mobility relative to other objects inside the mine. These hazards reduce the reliability of the system. Multiple input and multiple output schemes can improve the reliability and throughput of the system. Nonetheless, the presence of mobility and shadowing impacts the error rate of the signal. Here, we use an optimization method based on particle swarm optimization (PSO) to obtain optimal spatial parameters for the communication system. Numerical simulations prove the improvement compared to the previously used setting, allowing better reliability for the spatial multiplexing techniques by improving the link robustness over orientation changes.