The random access procedure in cellular networks suffers from a congestion problem caused by massive access requests from a large number of devices. Since this congestion problem causes inefficient energy consumption and increases the random access delay, an efficient random access procedure is required for various types of devices. In this paper, we propose a new access control scheme to reduce the access delay and the energy consumption by mining hidden random access resources. The proposed scheme consists of the random access procedure and the resource allocation algorithm. The proposed random access procedure utilizes the multiple access class barring (ACB) procedure to mine and utilize the hidden random access opportunities (RAOs) in order to increase the number of successfully admitted devices. The proposed algorithm optimizes the resource allocation parameters according to the estimated number of devices. We provide an analytical model for the proposed scheme by using an embedded Markov chain. The proposed scheme is shown to reduce the random access delay and the energy consumption for green communications by achieving 53 percent maximum efficiency compared to 37 percent in the conventional schemes with the ACB and random access procedure.