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Contemporary Stone Mining and Processing Technologies and China’s Experience in Importing Stone Equipment Authors: Zhang Decong, Cai Haikang China is rich in natural resources and possesses immense potential for development. Over the past 20 years since the reform and opening up, the stone industry has experienced astonishing rapid growth. Stone production increased from 400,000 m2 of slabs produced in 1978 (including terrazzo) to 4.8 million m3 of raw stone by 1998, which is equivalent to about 12 million tons. The production of marble and granite slabs exceeded 100 million m2, making it the second-largest stone-producing country in the world. There are over 8,000 existing stone mining and processing plants, employing 2.5 million workers. It has truly developed into a stone industry that integrates mining, processing, and equipment manufacturing, becoming an industry that is both ancient and modern, and one that attracts attention within the national economy. China’s stone resources are distributed across more than 30 provinces, municipalities, and autonomous regions, with over 1,000 different varieties. Of these, there are more than 600 types of marble and over 400 types of granite. It can truly be said that China boasts abundant resources, a wide variety of types, and diverse colors – something that no other country in the world can match. From a macroscopic perspective, China’s stone industry is at the forefront of the world in terms of production capacity, total import and export volume, equipment level, research capabilities, and design standards. Become a major stone industry power in the world. When it comes to the current status and future prospects of the global stone industry, Italy is by far the most representative example. The reason why Italy has become a world-renowned kingdom of stone lies in the fact that it has experienced research teams dedicated to mining and processing ； There is a highly experienced design team skilled in equipment development and creation ； Engineering and technical personnel capable of adapting flexibly to carry out actual mining and processing operations ； Thanks to well-informed stone and machinery associations that organized and coordinated mining, processing, and equipment manufacturing, and through half a century of relentless efforts, it has become a veritable stone kingdom that ranks first in the world in terms of total production and import-export volume, offers the widest range of products, and leads in the export of stone equipment. Italy’s greatest advantage lies in its possession of specialized stone mining equipment designed to suit various geological conditions, different rock types, and various mining methods ； There are specialized processing equipment for stone products designed to suit various types and specifications, as well as different production scales and applications; this ensures product quality, reduces consumption and costs, makes full use of the equipment’s manufacturing capacity, thereby increasing labor productivity and the overall efficiency of the enterprise, allowing it to remain at the leading position over the long term. Italy’s overall labor productivity: raw material extraction > 400, sheet processing > 2000. Over the past decade, as equipment manufacturing has advanced in terms of structure, performance, materials, and the application of new technologies almost in step with other mechanical and electrical industries, it is by no means easy to break through the current level and achieve a significant leap forward. The industry is currently at a stage of building up momentum; as a result, no truly transformative new processes, new equipment, or new methods have been introduced to date. However, the global stone processing equipment industry has seen the following changes and developments in recent years: 1. Highly automated, computer-controlled processing equipment was displayed, such as machines for shaping irregular shapes and performing contour carving ； Fully automated sheet metal production lines, etc ； 2. Equipment is scaled up to increase productivity per unit of time. For example, giant stone sawing machines with a double-link frame that can accommodate 150–200 saw blades, continuous grinding machines with 24 grinding heads, and two-way cutting machines equipped with 56–60 vertical saw blades. 3. Increase the motor speed or cutting linear velocity, such as in beaded diamond rope saws for cutting stone, etc. It is undeniable that there are still many gaps between our country and Italy. In particular, there is still a significant gap in areas such as corporate quality, and efforts from industry professionals are needed. First, stone mining in our country is characterized by a wide distribution, numerous sites, decentralization, and small scales; it is necessary to advance rapidly toward industrialization and intensification. In stone mining, which serves as the foundation of the stone industry, people are gradually emerging from the misconception of focusing more on processing rather than extraction. Many mines and quarries now pay close attention to geological studies and planning, and they employ advanced extraction processes, technologies, methods, and equipment in order to enhance the scientific approach to mining, improve economic efficiency, raise awareness of environmental protection, and ensure the rational use of resources. Stone mines have their own characteristics; they are completely different from other types of mines such as those in the metallurgy, non-ferrous metals, and chemical industries, which aim to obtain useful components. In theory, stone mines aim to produce as large and intact regular hexahedrons – namely rough stones – as possible. Therefore, the generally applicable mining methods and equipment are useless in stone quarries. The vast majority of stone mines in our country employ an open-pit mining method with steep slopes and high benches ； The road development and road transport plan is in line with the **region, where the stone industry is well-developed. The height of the steps ranges from 3 to 10 meters, and those exceeding 10 meters are not uncommon. The main difference from abroad is that on mountain roads there, the maximum vertical gradient is 25–30%, while the gradient of flat sections is over 15% ； In our country, no one has yet dared to go beyond the provisions of the mine road design standards, resulting in long road distances, high investment costs, and a low traffic density, which prevents the investment from yielding the desired returns. The mining processes in China’s stone mines generally consist of five main steps: separation, cutting, shaping, lifting, and transportation. Separation is a key process in stone quarrying, which involves separating the stone blocks from the rock mass in the quarry according to their defined three-dimensional dimensions. The height of the long rectangular blocks is generally equal to the height of the step, H (H=3~10m), while their length is a fraction of the length of the already formed working face, usually ranging from 10 to 30m. The volume of long rectangular blocks is several times to dozens of times that of the commercial raw material. This process is the same as those abroad in terms of technical concepts, equipment used, and separation methods. The cutting process involves breaking down long stone blocks into rough blanks according to the dimensions and requirements of the finished products. The shaping process involves removing the parts that do not meet the requirements for raw materials – including spots larger than the specified size, separated particles, color streaks, cracks, and uneven surfaces – and shaping them into uniform, dense, regular hexahedrons with a consistent color, thus producing the finished raw material suitable for use. The lifting (shoveling) process involves moving the raw materials into position, stacking them together, or lifting/shoveling them onto vehicles. Mast cranes, crawler cranes, or front-end loaders and forklifts are usually chosen. Make a reasonable choice based on different conditions. The transportation process refers to the removal of the raw goods from the quarry after they have been loaded and secured. Trucks without side panels and flatbed trailers are usually chosen. As can be seen from the above, the separation process is crucial in stone mining; it has a significant impact on the profitability of mines and plays a decisive role in improving the utilization rate of resources and reducing the amount of waste material. Therefore, accurately determining the three-dimensional dimensions of long rectangular blocks is a topic worthy of in-depth study by every mining technician. Based on domestic and international mining practices, the following factors should be considered when determining the dimensions of long rectangular blocks: 1. The properties of the rock, its splitting characteristics ； 2. Density and spacing of natural joints, cracks, and bedding planes ； 3. Specifications and requirements for raw materials of products ； 4. Performance and parameters of the separation equipment. The methods for separating long rectangular blocks are as follows: 1. Blasting method via drilling holes; this is further divided according to the blasting materials used into: A. Detonation cord blasting method B. Detonation tube blasting method C. Low-energy **(black**) blasting method. 2. Splitting method via drilling holes: this is divided according to the tools used into: A. Wedge-driving splitting method: single wedge and combined wedges ； B. Hydraulic splitting method by expansion; 3. Sawing separation method: Cutting is carried out using wire saws for stones, chain saws for stones, and diamond-bead wired saws for stones. 4. Combined separation method: That is, the combined use of the above three methods under different conditions. The aforementioned separation methods are also applicable to the segmentation (disassembly) process. The dense blast hole method, which was once used in the separation process, has gradually been phased out. Flame cutting is often employed to create free faces in granite mines, while methods such as high-pressure water jet cutting and plasma cutting are under investigation and testing, with breakthroughs expected in the near future. It is worth mentioning that the uniquely Chinese splitting wedge, which seems simple yet is actually highly scientific, has made an outstanding contribution to the exploitation of granite in our country. It is more time- and labor-saving than combined wedges, hydraulic splitters, and hole blasting; it is also economical and safe and reliable. Granite mines are still widely used in our country. Most stone mines in China are of small to medium size, with very few exceeding 10,000 m3. The specifications of the raw materials remain relatively small, which is related to various aspects of the mining process; some of the mining and transportation equipment is not suitable for use ； The limitations of some mining methods ； In some areas, transportation is inconvenient and the design standards for roads and bridges are low; these factors remain obstacles to keeping up with or even surpassing the advanced practices in stone mining. Changing the current situation of stone mines, which are scattered over a large area, numerous in number, and produce small quantities, and advancing rapidly toward industrialization and intensification, represents the hope for transforming China’s stone mining industry and creating a new outlook for it. Second, China’s stone processing industry needs to strengthen management, prioritize quality over quantity, and move toward a more organized, group-based structure. Through transformation, new construction, and the introduction of technology and equipment, China’s stone processing industry has seen its processing technologies and equipment reach the level seen in the international market during the 1980s and early 1990s. A number of large factories and industrial groups are operating successfully, and some of their products have entered the international market; as a result, China has become a major player in the stone processing industry. Stone processing equipment: After the mines produce qualified raw stone, aside from a small portion that is used for carving handicrafts, making tombstones, or as construction material, most of this raw stone goes to stone processing plants where it is turned into one of the following three types of sheets: 1) Ultra-thin sheets: with a thickness of ≤5 mm; 2) Thin sheets: with a thickness of 8–12 mm; 3) Standard sheets: with a thickness of 20 mm. Ultra-thin sheets are produced in very small quantities in China, but there is great potential for using them in combination with different materials to create high-quality decorative materials that are lightweight, luxurious, insulating, and soundproof. Based on their surface treatment, sheets are divided into polished sheets and rough sheets (dehairing and notching, sandblasting). Based on their rock properties, they are divided into marble and granite; natural slate is also classified as a third type of slab. Processing techniques for granite and marble slabs: The main processes are sawing, grinding, and cutting. First, the raw material is cut into rough slabs using mechanical saws; these rough slabs are then thickened through rough grinding, followed by rough (or fine) grinding and polishing to produce slabs without edges. Finally, they are cut into finished slabs using cutting machines according to specific specifications and requirements. Equipment used for sawing boards: 1. Frame-type steel grit stone sawing machine, available in both sliding and swinging types ； 2. Diamond frame stone sawing machine ； 3. Gantry-type diamond disc saw for cutting stone ； 4. Single and multi-diamond saw blade two-way cutting machine ； 5. Diamond rope saws and band saws. Plate grinding (polishing) equipment: 1. Multi-disc continuous grinder 2. Bridge-type grinder 3. Hand-held grinder. Plate trimming equipment: 1. Bridge-type trimmer 2. Cantilever-type trimmer 3. Vertical and horizontal multi-blade trimmer. Due to the varying hardness of rocks and the different specifications and requirements for products, different types of machinery are used accordingly. To produce standard marble slabs, frame-type diamond saw machines or gantry cutters with large-diameter diamond saw blades are typically used ； To produce thin sheets (or ultra-thin sheets), it is also necessary to edge them using an edge grinding and chamfering machine after cutting them into sheets of specified dimensions; the front side must also be chamfered before they can be packaged and shipped. In the production of ultra-thin sheets and certain fragile thin sheets, in order to improve the yield of finished products, the rough sheets processed by double-sided cutting machines or similar equipment are first ground and polished, after which they are split in half using a splitting machine before proceeding to the next processing step. When processing granite and marble slabs, the main factors considered in selecting equipment are: improving the yield of finished slabs and reducing production costs. A number of key enterprises have been established in the processing industry of granite and marble slabs, focusing on the comprehensive improvement of product quality, specifications, and variety. To compete on a large scale in the international market, it is necessary to improve processing precision, enhance the gloss of the surfaces, ensure product quality stability, upgrade packaging, and form several large-scale corporate groups that adopt an organized price competition mechanism in order to engage in long-term competition with major stone-exporting countries. Third, regarding stone mining and processing equipment as well as the experience in introducing such equipment, after 20 years of introduction, use, adaptation, imitation, and innovation, a number of manufacturers of stone processing equipment have emerged on a significant scale, with about 20 of them becoming key enterprises in the stone industry. These enterprises possess manufacturing capacity equipped to process approximately 80 million square meters of marble and granite. It can basically work in conjunction with Jackie Chan to form production lines, each with its own distinct features. For example: a granite standard slab production line equipped with main machines such as a translational steel-grit frame sawing machine, multi-head continuous polishing machine, and bridge-type cutting machine ； Marble and granite thin slab production line equipped with multiple two-way cutting machines, multi-head continuous grinding machines, cross-cutting machines, and edge grinding and chamfering machines as the main equipment ； A marble standard slab production line equipped with diamond saw blade frame stone sawing machines, multi-head continuous polishing machines, and bridge-type cutting machines as the main equipment. In recent years, gantry cutters equipped with large-diameter diamond saw blades have also been put into practical use in production lines as a replacement for frame-type stone sawing machines. These devices have contributed to the rapid development of China’s stone industry. Moreover, these devices are inexpensive, costing only 1/5 to 1/8 of the price of imported devices; they offer a significant price advantage, which is why the market is very active and they are highly popular among small and medium-sized enterprises. China Stone Network. However, due to the inherent problems of domestic equipment, compared with imported equipment, some of it has poor rigidity, low precision, and frequent failures; there are also issues related to both design and manufacturing in such equipment. Therefore, it is extremely difficult to introduce products on a large scale into the international market. China’s annual export volume is around 3.5 million tons, accounting for approximately 29% of its total production. This represents only about 15% of the total international trade in stone products, which is less than that of Italy, Spain, Portugal, and India. This is highly disproportionate to its status as the world’s second-largest producer. Moreover, the price of China’s export products is only 1/3 to 1/2 of the price of similar products in Italy. Meanwhile, 300,000 to 500,000 tons of finished panels still enter the Chinese market each year. In summary, how to balance factors such as equipment introduction, product export, and price competition is an issue worthy of study by industry professionals and experts. In our country, there are over 8,000 stone processing enterprises, including around 400 foreign-funded enterprises. Less than 10% of these enterprises operate at a significant scale and produce standardized products; in other words, more than 7,000 of them are small and scattered enterprises that lack the scale necessary for mass production. They are not in a position to compete on the international stage and can only sell low-quality, rough products at cheap prices in order to survive. Therefore, we have reason to believe that, in addition to transforming enterprises, improving management, and moving toward a more centralized and large-scale industrial structure, it is feasible to selectively introduce individual machines or complete sets of equipment to modernize our enterprises, and this is indeed what happens in practice. During the first decade after the reform and opening up, China spent around 700 million dollars to acquire approximately 150 sets of equipment for mining and processing operations ； The subsequent decade will cost around $1 billion to introduce more than 150 processing production lines. Our country is a major importer of stone processing equipment from Italy. In 1995, the total weight of equipment imported from Italy amounted to 9,000 tons, accounting for 70% of China’s total imports of such equipment and 12.7% of Italy’s total exports of it. The more than 300 stone production lines introduced over the past 20 years have a nominal production capacity of around 25 million m2, but most of these lines are far from reaching their nominal capacity. The reasons include management level, operational proficiency, issues related to the supply of spare parts and equipment maintenance; additionally, small raw material specifications are the direct cause. One thing is still certain: 80% of the products that enter the international market each year are produced on imported production lines. When comparing the two, the advantages of imported production lines are self-evident. Regarding the current situation and future prospects of the stone industry, it is essential to introduce key individual machines or complete stone production lines in a selective, appropriate, and controlled manner. First, there is no longer any need to introduce stone mining equipment. The 60 sets of marble and granite mining equipment that were introduced in the past, some of which are even stored in warehouses, need to be put into use as a top priority. Moreover, looking at the development of stone mining equipment abroad, there have been no significant new products in recent years; the capabilities of domestically produced equipment are generally sufficient to meet the needs of stone mines ； Second, the introduction of processing equipment should not be done by blindly pursuing larger and more advanced models. In the development of stone machinery manufacturing abroad, computer-controlled stone processing equipment and highly automated production lines have been introduced, as well as frame-type stone sawing machines equipped with 150 saw blades, two-way cutting machines with up to 56 vertical cutting blades, and continuous polishing machines with 24 grinding discs, among others. If it is advisable to build one or two demonstration production lines, blindly pursuing higher levels or larger scales does not suit China’s national conditions. We analyzed a frame-type stone sawing machine using 150 saw blades. The volume of raw material required for processing (when the saw is fully loaded) is 25 cubic meters, with a weight of around 70 tons. Under optimal operating conditions, two pieces of such raw material can be combined to form one piece; thus, for rocks weighing 35 tons each, the difficulties involved in transporting them from the mining site to the processing plant are considerable. Although lifting and transportation equipment might be able to address this issue, since stone mines are located in remote areas with poor transportation infrastructure, and most roads and bridges there meet low design standards, these elements become major obstacles to the development of these mines. If small-sized raw materials are used in triple or quadruple assemblies to accommodate such a massive structure, it is better to adapt the solution to local conditions and make an appropriate selection by taking all relevant factors into consideration. Third, we have brought in over 300 production lines to fully utilize their manufacturing capacity. Establish a national parts center for imported stone processing equipment to enhance major repairs and maintenance ； At the same time, strengthen the training of personnel on duty to ensure they master the operational techniques proficiently ； Ensure that the established production line truly delivers its benefits. Fourth, for the production lines currently equipped with domestic machinery, individual machines are purposefully introduced to improve product quality. Emphasis is placed on mass production to create high-quality products with uniform thickness, no color variation, and consistent gloss, thereby enhancing their competitiveness in the international market.