We developed the wave roller pre-screening machine and used it in sandstone mines. This pre-screening machine can separate the sticky wet material out from the sandstones. Then the sandstones can be crushed in one stage crushing by hard rock impact type crusher. The wave roller pre-screening machine can bear the impact load of large ores and meet the needs of pre-screening. It also has self-cleaning function, which can eliminate the adhering of sticky wet materials. The machine can run steadily. The wave roller pre-screening machine will do pre-screen for low grade raw materials and improve the quality of the materials so the raw materials can become the useful ores. Screening the sticky wet materials out can eliminate the crusher blockage. What's more, the pre-screening for raw ores whose particle size is qualified can reduce the wear of crusher and reduce the using of the over-crushing. Along with the continuous maturity of wave roller pre-screening technology, there are many large machines used in limestone pre-screening one stage crushing system. For the limestones with larger abradability, two-stage crushing is usually used. The coarse crushing is using jaw crusher or gyratory crushers. The crusher that is used in medium crushing is mainly decided by follow-up mills. If grinding the raw materials for ball mill, the hammer medium crusher can be selected for its products and the fine powder content is higher. If the follow-up crusher is vertical roller mill, the medium crushing can choose the cone medium crusher. If the ores with qualified particle size will be selected out after the coarse crushing, the specification of medium crusher can be lower and this selection plays the role of energy saving. For limestone deposits of fourth mulch, its ingredients correspond with ingredients requirements. So it can not be peeled and can be used as clay materials. Crushing the mixture of the two materials is a crushing method which is more economic. If the second material that is used in plant is the clay with high plasticity and water content, the separate processing, transportation and storage of clay are very hard. Under the circumstance, it is better to crush the mixture of clay and limestone. Although the half continuous production of the mining is significant energy-saving, it also has higher requirements for crushing system. jaw crusher:http://www.crusher-machine.com/1.html ball mill:http://www.hxjq-crusher.com/20.html