###### Abstract  
In coal mining, solid backfilling technology is widely used. However, its efficiency is seriously hindered by the following two factors. Firstly, the process flow of the solid backfilling operation is more complicated in the back, and the spatiotemporal linkage (SPL) between actions of the cylinders powering each support and between hydraulic supports in the whole face lacks continuity. Secondly, the coal mining process in the front has a higher level of intelligence and technical maturity than the backfilling operation in the back, the latter permanently staying behind the former. To this end, the present study investigates the SPL of the mining and backfilling operations for single supports in the working and whole faces. The SPL of cylinder actions is analyzed for intelligent backfilling using hydraulic supports. We also investigate the SPL of the positions of each piece of key equipment involved in different steps of intelligent backfilling in the whole face. Formulas are derived for calculating the time required to complete the cyclic hydraulic support movement-discharge-filling operation for single supports and the whole face. The key factors influencing the time required to complete a hydraulic support movement-discharge-filling cycle are analyzed. On this basis, a backfilling efficiency optimization scheme is proposed. It envisages reducing the number of mappings and time gaps in actions of single supports and cylinders, increasing the number of hydraulic supports in parallel operation, and intelligent upgrading of the backfilling operation. These findings help synchronize coal mining and backfilling operations. intelligent backfilling; mining and backfilling operation; spatiotemporal linkage; parallel mining and filling +
Footnote †: journal: Applied  
Article  
Solid Backfilling Efficiency Optimization in Coal Mining: Spatiotemporal Linkage Analysis and Case Study  
[PERSON]  
1 School of Mines, China University of Mining and Technology, Xuzhou 22116, China;  
[EMAIL_ADDRESS] (T.Z. );  
tx22020033a41 ddcumt.edu.cn (K.Y. );  
[EMAIL_ADDRESS] (Y.W. );  
[EMAIL_ADDRESS] (Y.H. );  
tx22020048a31 ddcumt.edu.cn (H.L. );  
[EMAIL_ADDRESS] (I.C.) [EMAIL_ADDRESS] (I.C. diameter backfill pipelines and a fast and precise preparation and control technique for non-cemented slurry. [PERSON] et al. [8] employed automatic control technology and intelligent recognition and processing technology for the automated control of cemented backfilling, improving the tailings backfill quality. [PERSON] et al. [9] systematically elaborated on an overall framework for underground intelligent sorting and an in situ backfill for deep coal mines for solid backfilling and mining-selection-filling processes. They built an overall research framework and equipment system for underground intelligent sorting and in situ backfill for deep coal mines. A novel solid backfilling mining technology that integrated mining, sorting, and backfilling and achieved the original underground gangue's sorting and an in situ backfill was proposed in works [10; 11] [PERSON] et al. [12] installed support pressure, angle, stroke, and blanking height sensors to transmit data to the central controller. A control program was used for conditional judgment of the gangue filling rate and compaction degree, thereby realizing the process flow of gangue backfilling control automation. [PERSON] et al. [13] studied machine-following automation for fully mechanized mining hydraulic supports that consisted of three stages: automation of center following, automation of head following, and automation of tail following. Then, based on the action flow for hydraulic supports and the motion trajectory of the shearer, the automated process flow of the machine head and tail following was subdivided into six stages. [PERSON] et al. [14] proposed a collaborative control technology for the shearer and hydraulic supports in a fully mechanized working face based on memory cutting performed by the shearer and automated following control technology for hydraulic supports.