An employee had just finished lifting a shale bin using two loaders (one with a stinger, chain, and lifting equipment) in order to place matting underneath. Once the matting was in place, the employee directed the loader to lower the bin until there was enough slack in the lifting chain to remove it. As the employee grabbed the eye of the lifting chain to unhook it, the operator of the loader bumped the controls with his knee, causing the chain to tighten and pinch the employee's right middle finger between the bin and the chain. The employee's right middle finger was amputated between the middle and upper joint, and the employee was hospitalized.