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ROCK DRILLING AND BLASTING SYSTEM WITH LIQUID CARBON DIOXIDE (CO₂) IN UNDERGROUND COAL MINES The Rock Drilling and Blasting System using Liquid Carbon Dioxide (CO₂) in underground coal mines is a system that, while performing excavation through a blasting-like mechanism, is not classified as an explosive. Therefore, no special permits are required for storage, transport, or use. The system works by heating liquid CO₂, causing a phase transition into gas, resulting in powerful thrust that penetrates the smallest cracks within the rock or coal seam, causing them to break apart and be pushed toward the free face. Unlike conventional explosives, phase-transition CO₂ systems do not cause fragmentation but rather crack the rock. During this process, CO₂ penetrates in a wedge-like fashion into the tiniest fractures, and due to the diabatic expansion and energy drawn from the internal system, the temperature drops to as low as -78°C, pushing broken pieces 1 to 2 meters toward the open face in large fragments. The system involves a special steel tube filled with phase-transition CO₂, which is inserted into pre-drilled holes of suitable depth and diameter. The steel tube, with 120 MPa strength, consists of a heater and a rupture disc. It is connected via filling or cable interfaces to 12V DC battery sources and/or anti-gas detonators (igniters). The heater heats the liquid CO₂ to 1170°C, causing a volume expansion of 600 times, resulting in an internal pressure of 250 MPa (2.5 tons/cm²). This pressure breaks the rupture disc and causes the gas to be released supersonically through nozzles at the tube’s end. This discharge occurs within milliseconds and resembles a shockwave, mimicking explosive blasting. However, since it produces no vibration, dust, or fragment projection, the effect is defined as cracking rather than blasting. THERMAL CYCLE DIFFERENCE BETWEEN PHASE-TRANSITION CO₂ AND CONVENTIONAL EXPLOSIVES During the sudden release of CO₂ gas, a significant cooling occurs, dropping the environment to -78°C. In contrast, conventional explosives (e.g., dynamite) raise the environment's temperature up to +2800°C. Most coal seams are highly susceptible to spontaneous combustion, and the intense heat from dynamite can lead to major fires and methane (firedamp) explosions. Notably, fatal explosions at the Soma and Amasra Hard Coal Enterprises in Turkey were due to such fires triggered by conventional blasting. APPLICATION BY T.C. TURKISH HARD COAL ENTERPRISE (TTK) Trials of the CO₂ system were conducted in 1997 and 2002 at the Amasra Underground Hard Coal Enterprise but were unsuccessful. In 2004, trials resumed at the same facility. The CARDOX System, in use globally since 1956, was modified with a new hole design and blasting head, resulting in 2 to 2.5 times more coal production. Positive results were also obtained in rock excavation with modified blasting heads. Various successful field applications were achieved across multiple TTK operations, including inclined, vertical, and horizontal coal seams, as well as galleries, crosscuts, and headings. TECHNICAL JUSTIFICATION FOR PHASE-TRANSITION CO₂ SYSTEM The system ensures more efficient fracturing, especially in hard rock formations, with almost zero toxic chemical emissions. It significantly improves the performance of excavation and loading machines, and its cooling effect provides a crucial safety advantage in coal mining. In areas where mechanical excavation is not feasible, blasting becomes essential. The choice of blasting method has critical effects on overall mining efficiency. Therefore, customizing blasting parameters based on geological and physical site characteristics is vital—and the Phase-Transition CO₂ System emerges as a key alternative. TOXIC EFFECTS OF CONVENTIONAL BLASTING WITH DYNAMITE IN UNDERGROUND COAL MINES Based on a 15-day time-study conducted at TTK Amasra: Coal production areas: Workers were exposed to 150–300 ppm CO for at least 4 hours/day. Development headings: Workers exposed to 400–500 ppm CO for at least 2 hours/day. According to the Occupational Health and Safety Commission, acceptable CO exposure levels are: CO Level (ppm) Safe Exposure Time (No Device) 50 8 hours 100 2 hours 200 1 hour 300 30 minutes 500 2 hours – Fainting 1000 1 hour – Fainting 2000 30 minutes – Fainting 3000 Minutes – Death These values suggest that pneumoconiosis and other occupational diseases are inevitable under current conditions. A large portion of TTK’s compensation payments are due to health issues from dynamite use. If CO₂ systems were adopted, occupational disease compensation costs and fatal accident claims could drop by up to 70%. CONCLUSION On 26/06/2005, I presented an addendum report to the TTK General Directorate Productivity Department, countering a negative evaluation of the CO₂ system with a positive technical report. This report urged immediate discontinuation of highly toxic and explosive-based dynamite usage and the urgent implementation of the Phase-Transition CO₂ Drilling and Blasting System. Since 2014, Chinese companies have led the world in adopting this system under the name "CDPTB" in surface mining benches, underground coal operations, and infrastructure projects (like subways). They even banned dynamite in 2021, promoting the system as a clean energy-aligned, environmentally friendly solution. While adapting the system to surface mines is relatively easy, applying it to underground galleries and coal seams requires high technical skill—which we demonstrated successfully. Had the project continued, it could now be a global technological export aligning with climate protocols like the Paris Agreement, potentially even surpassing CO₂ capture technologies by preventing emissions and eliminating toxic explosives. A NOTE FOR COMPETITION CONSIDERATION Although not classified as an explosive, the Phase-Transition CO₂ Drilling and Blasting System achieves 237–285 MPa internal tube pressure, yet only transmits 4.7 to 5.2 MPa pressure to the rock. One might ask how such pressure can break rock with 50–250 MPa strength. This project is based precisely on this principle—and we stand by its validity
