Stainless Steel Coil Tube (Coiltube) for In-Situ Leaching Uranium Mining Applications
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 612) is a precision-engineered flexible tubing system specifically designed for the In-Situ Leaching (ISL) Uranium Mining industry. This product represents a critical component in the automatic coiling and deployment apparatus used for subsurface injection and extraction operations in uranium ore recovery. The coil tube is engineered to withstand aggressive chemical environments, high differential pressures, and sustained mechanical stresses encountered during the continuous injection of leaching solutions and recovery of uranium-bearing solutions from underground formations.
This product has been validated through extensive field deployment in the context of automatic coiling device systems, demonstrating reliable performance in both injection wells and production wells used for in-situ uranium extraction processes. The design philosophy emphasizes corrosion resistance, mechanical durability, flexibility for coiling/deployment, and long-term service life under chemically aggressive conditions.
Material & Properties
Base Material Composition
The coil tube is fabricated from high-grade Stainless Steel (奥氏体不锈钢), specifically selected for its superior resistance to chloride-induced stress corrosion cracking and general chemical attack. The primary alloy grades utilized include:
- 316L Stainless Steel (UNS S31603) — Low-carbon austenitic grade with added Molybdenum (2.0–3.0%) for enhanced pitting and crevice corrosion resistance
- 304L Stainless Steel (UNS S30403) — General-purpose austenitic grade for moderate corrosive environments
- 316Ti Stainless Steel (UNS S31635) — Titanium-stabilized variant for applications requiring resistance to sensitization during welding
Key Mechanical Properties
- Tensile Strength (抗拉强度): ≥ 520 MPa (316L), ≥ 485 MPa (304L)
- Yield Strength (屈服强度): ≥ 205 MPa (316L), ≥ 170 MPa (304L)
- Elongation (延伸率): ≥ 40% at break (ensuring formability for coiling operations)
- Impact Toughness: Retained at temperatures ranging from −196°C to 600°C (austenitic structure)
- Hardness: ≤ 200 HB (annealed condition)
Chemical Resistance Characteristics
- Excellent resistance to dilute sulfuric acid (H₂SO₄) concentrations up to 10% at ambient temperature
- Superior performance in chloride-containing solutions (relevant to underground brine environments)
- Resistance to hydrofluoric acid (HF) solutions used in uranium leaching circuits
- Stable in alkaline environments (pH 8–12) typical of uranium-bearing groundwater
- Non-magnetic in the annealed condition
Specifications
| Parameter | Specification | Standard/Reference |
|---|---|---|
| Product Category | Coil Tube (盘管) — Flexible Tubing for Subsurface Deployment | — |
| Outer Diameter (OD) | 12 mm – 50 mm (customizable per project requirements) | GB/T 14976 / ASTM A511 |
| Wall Thickness | 1.0 mm – 3.0 mm | GB/T 14976 |
| Coil Diameter | 300 mm – 1500 mm (adjustable per deployment geometry) | Manufacturer Specification |
| Coil Length (per spool) | 50 m – 500 m (configurable) | — |
| Material Grade | 316L / 304L / 316Ti (selectable) | ASTM A213 / GB/T 13296 |
| Surface Finish | Pickled & Passivated (Ra ≤ 0.8 μm) | ASTM A380 |
| Maximum Working Pressure | ≤ 1.6 MPa (standard); up to 4.0 MPa (reinforced variants) | ASME B31.3 |
| Operating Temperature Range | −40°C to +250°C | — |
| Bending Radius (minimum) | ≥ 5 × OD (ensuring no wall thinning or kinking) | GB/T 14976 |
| Welding Method | Automatic Argon Arc Welding (TIG/GTAW) with backing gas | GB/T 12467 |
| End Treatment | Beveled ends with protective caps; threadable or flange-ready | — |
| Corrosion Allowance | 0.5 mm – 1.0 mm (design margin) | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorously controlled multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical integrity, and corrosion resistance:
- Raw Material Selection & Inspection: Hot-rolled stainless steel coils conforming to ASTM A240 or GB/T 3280 are procured with full chemical composition verification via Optical Emission Spectroscopy (OES) and mechanical property certification.
- Cold Drawing (冷轧/冷拔): The coil is cold-drawn through precision tungsten carbide dies to achieve the specified outer diameter and wall thickness tolerances (±0.05 mm OD tolerance). This process induces beneficial work hardening while maintaining ductility.
- Intermediate Annealing: Where required, the drawn tube undergoes solution annealing at 1050–1100°C followed by controlled water quenching to restore full austenitic structure and eliminate residual stresses.
- Precision Coiling: Using automated coiling machinery (as described in the referenced automatic coiling device research), the tube is wound onto spools with controlled tension to prevent deformation, ovality, or springback. The coiling process is monitored by inline dimensional sensors.
- Pickling & Passivation (酸洗钝化): The finished coil tube undergoes chemical pickling (HNO₃/HF blend) to remove surface scale and contaminants, followed by passivation treatment to establish a protective chromium oxide (Cr₂O₃) film on the surface.
- Hydrostatic Pressure Testing: Each coil is subjected to hydrostatic testing at 1.5× the maximum working pressure for a minimum dwell time of 60 seconds to verify structural integrity and absence of leakage.
- Final Inspection & Certification: Non-Destructive Testing (NDT) including eddy current testing (ECT) and visual inspection are performed. Each batch receives a Material Test Report (MTR) with full traceability documentation.
Applications
Primary Application: In-Situ Leaching (ISL) Uranium Mining
The coil tube serves as the primary fluid conveyance medium within the automatic coiling deployment system used in in-situ uranium mining operations. Key application scenarios include:
- Injection Wells: Transporting acid leaching solutions (typically H₂SO₄-based, pH 2–4) into uranium-bearing aquifers for ore dissolution
- Production Wells: Recovering uranium-bearing pregnant leach solutions (PLS) from the ore body to the surface processing facility
- Recovery Wells: Facilitating groundwater recovery and environmental remediation operations
- Automatic Deployment Systems: Enabling rapid, controlled lowering and retrieval of tubing strings into boreholes without requiring individual joint connections
Secondary Applications
- Geothermal energy extraction systems
- Chemical processing plant flexible piping
- Hydrogeological monitoring well instrumentation
- Oil and gas well completion tubing (non-sour service)
- Water injection and dewatering systems in mining operations
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality assurance systems and adheres to the following international and national standards:
| Standard/Organization | Scope of Compliance |
|---|---|
| ISO 9001:2015 | Quality Management System certification |
| ISO 14001:2015 | Environmental Management System |
| GB/T 14976 | Chinese National Standard — Seamless Steel Tubes for Fluid Transport |
| ASTM A511 / A213 | American standards for seamless austenitic stainless steel tubing |
| GB/T 13296 | Seamless Stainless Steel Tubes for Heat Exchangers and Heat Sinks |
| ASME B31.3 | Process Piping design and construction requirements |
| API 5L (reference) | Material quality and testing methodology |
Unique Selling Points
- Field-Proven Design: Validated through deployment in actual ISL uranium mining operations, with documented performance data from the automatic coiling device research program
- Integrated Coiling Technology: Manufactured to specifications compatible with automated coiling/deployment systems, enabling rapid well intervention and reduced operational downtime
- Superior Corrosion Performance: 316L grade with titanium stabilization option provides exceptional service life in aggressive leaching environments containing chlorides, fluorides, and sulfuric acid
- Full Traceability: Each coil is accompanied by complete material documentation, including mill certificates, chemical analysis, mechanical test reports, and NDT results
- Custom Configurations: Flexible manufacturing capability to accommodate project-specific requirements for diameter, wall thickness, coil length, and end fittings
- Cost-Effective Solution: Continuous coil configuration eliminates field welding requirements, reducing installation costs and eliminating potential leak points
Technical Notes
Storage & Handling: Coils should be stored in a dry, ventilated area away from direct contact with carbon steel to prevent galvanic corrosion. Protective end caps must remain in place until installation. Transport should utilize appropriate coil saddles to prevent deformation.
Installation Considerations: Minimum bending radius must be maintained during deployment. The tube should be deployed at a controlled speed to prevent dynamic loading and whip effect. Compatibility with wellbore casing diameter must be verified prior to installation.
Service Life: Expected service life exceeds 10 years under standard ISL operating conditions, subject to proper installation practices and periodic inspection intervals.