First select a site that is close to the raw material supplies such as your rock and sand. Some of my international producers will even locate their plants on the same site as the aggregate quarry. This is to save time and freight cost of the aggregates to the batching plant.
Compare the saving with the transportation cost of cement which is your most expensive material cost. Confirm the obtainability of securing 3 Phase electrical industrial power which is required for most concrete batching plant operations. At the same time, you should be researching if building permits, zoning approvals, air quality and noise level clearances would be required in the area you are considering.