Manual of Operation
for the SYOGM Rothensteed Mill
Table of Contents
- Description of the SYOGM Rothensteed Mill
- Machine Parts
- Capacity
- Water Input
- Wear Parts
- Motor Operation and Maintenance
- Operating the Feeder
- Screen Information
- Improving Gold Recovery
- Safety Precautions
- Installation and Commissioning
- Daily Operator Checks
- Lubrication Schedule
- Troubleshooting Guide
- Maintenance Schedule
- Storage and Decommissioning
- Technical Specifications
- Spare Parts List
- Operator Log Sheet
1. Description of the SYOGM Rothensteed Mill
The SYOGM Rothensteed Mill is purpose-built for the efficient milling of half-inch particles to pass through a 1.5 mm screen, drawing upon established research published in the Journal of the South African Institute of Mining and Metallurgy. This research demonstrated that gold recoveries in the range of 75 to 80 percent could be achieved at relatively coarse grinds. Notably, Vaal Reefs ore yielded a 75 percent gold recovery with no milling at all—merely crushed to pass 1.5 mm—and recovery increased marginally to 79 percent at 93 percent passing 74 microns as milling continued.
The mill is designed for direct integration with fine gold recovery sluices, including those utilizing Cleangold technology and methods. This configuration eliminates the need for material transport, minimizes dust generation, and enables immediate gold recovery upon milling. With trained operators, full gold recovery potential may be realized.
Detailed documentation regarding the fine gold recovery system, associated management policies, and operator training is provided in separate attached documents.
2. Machine Parts
- Support stand with legs – Provides structural foundation for the mill assembly.
- 10 HP motor, 3 phase, 1440 RPM – Main power unit. Full load amperage: 15.6 A at 415 V.
- Motor starter assembly – Includes starter unit, control wiring, ammeter, overload relay set to 15.6 A, and safety key switch.
- Three Type A V-belts – Power transmission from motor to rotor.
- Main milling assembly – Housed within the stand, comprising rotor, rotating impact plates, and 16 static impact plates; complete with safety covers.
- Feed hopper – Accepts input of half-inch sized rock material.
- Output screen – Positioned atop the discharge chute for particle size classification.
- Discharge sluice – Directs milled material to the gold recovery system.
- Plummer block bearings – Heavy-duty split-type bearing housings supporting the main rotor shaft. Designed to accommodate misalignment and withstand continuous impact loads. Require periodic greasing and inspection.
3. Capacity of SYOGM Rothensteed Mill
Under optimal operating conditions—including appropriate feed rate, particle size consistently smaller than half-inch, adequate water flow, correctly sized screen, and full motor power at rated speed—the SYOGM Rothensteed Mill consistently processes between 3 and 5 tonnes per hour.
It is important to note that feed rate significantly influences throughput; both underfeeding and overfeeding can negatively impact capacity. Operators should monitor and maintain steady feed delivery to achieve rated performance.
The use of dirty or turbid water may cause fine particles to cement inside the machine, leading to reduced efficiency and potential blockages. It is strongly recommended to clean the mill thoroughly using a pressure washer after each production shift and prior to any extended storage period.
4. Water Input
The SYOGM Rothensteed Mill is capable of operating in both dry and wet modes. Wet operation is strongly preferred for dust suppression, particle suspension, and optimal material flow.
A water flow rate of 1000 liters per hour is recommended for standard operation. The machine may function at reduced flow rates down to 500 liters per hour; however, operators should anticipate reduced throughput and increased dust generation under such conditions.
Water should be introduced at the feeder inlet simultaneously with the feed material to ensure uniform moisture content throughout the milling chamber.
5. Wear Parts
The following components are subject to wear and require periodic inspection and replacement:
- 16 static wear liners – Positioned circumferentially around the rotor; these endure continuous impact and abrasion.
- 3 static impact plates – Fabricated from 20 mm machine steel, reinforced with manganese welding lines for extended service life.
- Plummer block bearings – Supplied with standard grease nipples. Bearing life depends on operating conditions, contamination control, and lubrication discipline. Replace if excessive radial play or overheating is detected.
Wear parts should be replaced immediately upon noticing a measurable decline in milling capacity, increased processing time to achieve target particle size, or visible degradation of the impact surfaces.
Additional replaceable items include:
- 3 Type B V-belts – Supplied with the machine; replace when signs of glazing, cracking, or slippage appear.
- Pulleys – May require replacement depending on operational hours and belt tensioning practices.
- Screens – Various mesh sizes available; replace when worn, torn, or blinded.
Standard wear parts are provided sufficient for approximately three months of continuous operation under normal conditions.
6. Motor Operation and Maintenance
The mill is designed for use with a 7.5 kW (10 HP), 3-phase, 4-pole electric motor operating at 1440 RPM, constructed with full copper windings. Full load amperage: 15.6 A at 415 V.
This manual does not cover detailed motor maintenance or repair procedures; refer to the motor manufacturer’s documentation for servicing instructions.
Starter Operation
The motor starter unit is equipped with a clear control interface:
- Green button – Starts the motor.
- Red button – Stops normal operation.
- Emergency halt – Immediately cuts all power; push in an emergency, twist to release.
- Key switch – Disables starter operation when in the off position; key must be under control of authorized personnel only.
- Ammeter – Displays motor current draw during operation.
Only trained and authorized operators shall operate the starter or access the key-locked controls.
Overload Relay
The thermal overload relay is factory set to 15.6 A. Do not adjust. If the relay trips:
- Switch off and isolate power.
- Allow motor to cool for 15 minutes.
- Investigate cause of overload (excessive feed rate, screen blinding, mechanical binding).
- Rectify fault.
- Reset overload relay by pressing reset button.
- Restart per normal procedure.
Repeated tripping indicates a serious problem; do not bypass or increase overload setting.
7. Operating the Feeder
The feeder is designed to accept material from a conveyor belt system. It performs best under a balanced, consistent feed rate, synchronized with water addition.
Operators should be aware that improperly fed material or excessive air movement may cause fine particles to be expelled from the feeder opening. It is the final operator’s responsibility to adapt the feeder configuration to site-specific conditions.
Once the conveyor belt is installed and aligned, all unnecessary openings on the feeder should be securely closed or covered to contain dust, prevent spillage, and protect personnel from flying debris.
Feed rate guidelines:
- Start-up: Begin at approximately 1 tonne per hour.
- Ramp-up: Increase gradually over 30 minutes while monitoring motor amperage.
- Target amperage: 10.9–14.0 A (70–90% of FLA).
- Maximum: Do not exceed 15.6 A continuous.
Signs of incorrect feed rate:
| Symptom | Probable Cause | Action |
|---|---|---|
| Amperage <10.0 A | Underfeeding | Increase feed rate |
| Amperage >15.6 A | Overfeeding | Reduce feed rate immediately |
| Fluctuating ammeter | Surge feeding | Stabilize feed rate |
| Mill plugging | Feed rate too high | Stop feed; clear mill; reduce rate |
8. Screen Information
The SYOGM Rothensteed Mill is designed to accommodate a range of screen sizes, offering operational flexibility. When configured with appropriately sized screens, the mill can function as a mid-stage crusher reducing material to 3/8 inch, or as a fine grinder achieving products as fine as 30 mesh.
For gold liberation applications, a 1.5 mm screen opening is strongly recommended. This configuration aligns with the published research indicating near-optimal gold recovery at this particle size with minimal over-grinding.
Screen Replacement Procedure
To replace the screen:
- Stop mill and isolate power. Remove key from starter.
- Allow rotor to come to complete stop.
- Remove bottom output chute assembly:
- Release clamps or undo retaining bolts.
- Carefully lower chute; support weight.
- Remove worn screen:
- Note orientation for correct reinstallation.
- Remove retaining bars or wedges.
- Inspect screen frame and gasket; clean sealing surfaces.
- Install new screen:
- Ensure correct mesh size.
- Seat fully in frame.
- Secure with all retainers.
- Reinstall output chute:
- Check gasket condition; replace if compressed or torn.
- Tighten fasteners evenly.
- Rotate rotor by hand; confirm no contact with screen.
- Restore power; perform test run.
Screen life log: Record installation date, operational hours, and reason for replacement.
9. Improving Gold Recovery
Operators seeking to maximize gold recovery may integrate additional classification equipment downstream or in closed circuit with the mill. Suitable options include:
- Spiral classifiers – Use a rotating spiral shaft to settle and transport coarse material from fine overflow, ideal for closed-circuit milling.
- Hydro-cyclones – Employ centrifugal force to separate particles by size and density, with underflow returning to the mill and overflow reporting to recovery.
- Vibrating mesh screens with conveyor belt take-offs – Provide continuous screening of mill discharge, diverting oversize material back to the feed via integrated conveyor belts.
- Recirculating classifier wheels – Air-swept dynamic classifiers that reject oversize particles back to the mill while permitting fine product to pass through to collection.
These devices enable tighter control over particle size distribution and improve recovery efficiency by ensuring optimal feed to concentration equipment. Separate instruction manuals and operational guidelines are provided with each supplementary component.
10. Safety Precautions
The safety of all personnel is paramount. The following precautions must be observed at all times:
Personal Protective Equipment (PPE)
- Approved safety goggles must be worn by all personnel in the vicinity of the operating mill.
- Hearing protection is required during operation; sound levels may exceed 85 dB(A).
- Steel-toed safety boots are mandatory in the milling area.
- Dust mask or respirator (P2 or N95 rated) must be worn during dry operation or when handling dusty materials.
- Gloves must be worn when handling wear parts, screens, or cleaning debris.
Operational Safety
- Only rock material of specified size shall be introduced into the mill. No foreign objects.
- All incoming material must be inspected and trash removed—including plastic, wood, plant matter, and non-mineral debris—prior to feeding.
- Wet operation is strongly preferred to suppress dust. Inhalation of crystalline silica dust is a known cause of silicosis, a serious and irreversible lung disease.
- If dry operation is absolutely necessary, all machine openings, feeder inlets, and discharge points must be enclosed with careful nylon wrapping or equivalent dust-tight shrouding to prevent airborne dust migration.
- Never open inspection covers or access doors while rotor is moving.
- Lock out and tag out (LOTO) power source before any maintenance, cleaning, or adjustment.
- Keep hands, tools, and clothing clear of moving parts.
- Do not wear loose clothing, jewelry, or unsecured long hair near operating machinery.
Electrical Safety
- Only licensed electricians shall access starter interior or perform electrical work.
- Verify isolation before touching any electrical component.
- Do not operate machine with damaged cables or plugs.
- Report any shock, tingle, or tripping breaker immediately.
Housekeeping
- Maintain clean work area; slip hazards include water, spilled fines, and grease.
- Store tools and spare parts in designated locations.
- Ensure emergency stop is clearly visible and unobstructed.
Emergency Procedure:
- Push emergency stop.
- Call for assistance.
- Administer first aid if trained and safe to do so.
- Isolate power at main switch.
- Report incident to supervisor.
11. Installation and Commissioning
Site Preparation Requirements
The SYOGM Rothensteed Mill requires a level, reinforced concrete foundation capable of supporting the combined static and dynamic loads of the machine, motor, and feed system. A minimum concrete thickness of 150 mm with appropriate reinforcement is recommended.
Clearance requirements:
- Minimum 1 metre clearance on all sides for maintenance access.
- Minimum 2 metres overhead clearance for lifting and rotor removal.
- Minimum 1.5 metres clearance at discharge end for sluice and recovery equipment access.
Drainage:
- Floor must be sloped away from the mill base to prevent pooling of process water.
- Provision for a collection sump or drainage channel at the discharge end is essential for wet operation.
- Electrical components must be positioned above expected floor water levels.
Anchor bolts shall be cast into the foundation according to the mounting footprint diagram provided in Appendix A. Allow minimum 7 days curing time before placing equipment.
Lifting and Handling Instructions
Machine weight: Approximately 850 kg (motor not included).
Lifting points:
- Two lifting lugs are welded to the main frame top rail.
- Do not lift from rotor shaft, motor mounting plate, or feeder assembly.
Procedure:
- Use spreader bar with chains or synthetic slings rated minimum 2 tonnes capacity.
- Attach all four lifting points evenly; adjust sling lengths to maintain level lift.
- Lift slowly; clear floor by 100 mm and check stability before proceeding.
- Guide machine onto foundation bolts; lower carefully and engage nuts finger-tight.
Moving without crane:
- Pallet jack or forklift may be used from the side only, engaging frame base rails.
- Never lift machine from motor end only.
Alignment Procedure between Motor and Mill Pulleys
Correct pulley alignment is critical for belt life, power transmission, and bearing longevity.
Tools required: Straightedge, steel rule, or laser alignment tool.
Procedure:
Rough alignment:
- Mount motor on slide rail base; leave bolts snug but movable.
- Install motor pulley and mill pulley; ensure both are fully seated on keyways and shaft ends are flush with pulley hubs.
- Place motor pulley approximately 5–10 mm closer to motor than mill pulley to allow for belt tensioning take-up.
Angular alignment:
- Place straightedge across outer faces of both pulleys.
- Adjust motor position until straightedge contacts both faces evenly across full width.
- Repeat at top, centre, and bottom positions.
Parallel alignment:
- Measure distance between pulley centre lines at both front and back of pulleys.
- Adjust until both measurements are equal within 0.5 mm tolerance.
Final torque:
- Tighten motor mounting bolts to specified torque (refer to motor manufacturer data).
- Re-check alignment; slight shift may occur during tightening.
Belt Tensioning Procedure
Belts supplied: 3 × Type A V-belts.
Procedure:
- Install belts over pulleys by hand; do not roll or pry belts into grooves with tools.
- Adjust motor position outward on slide rail until belts are snug.
- Apply tension:
- Correct deflection: 10–12 mm downward force at belt mid-span when pressed firmly with thumb.
- Alternative method: Belt should not slip under full load but should not run hot.
- Run machine for 15 minutes; stop and re-check tension.
- Re-tension after first 8 hours of operation as initial bedding-in occurs.
Caution: Over-tensioning shortens bearing and belt life. Under-tensioning causes slippage, glazing, and capacity loss.
Electrical Connection Requirements
Motor specifications:
- 10 HP (7.5 kW), 3 phase, 1440 RPM, 4 pole.
- Full copper windings.
- Full load current: 15.6 A at 380 V, 50 Hz.
Connection requirements:
Supply cable:
- Minimum 4 mm² × 4 core armoured cable (3 phases + earth) – suitable for 15.6 A continuous duty.
- Cable entry via base of starter enclosure; use appropriate gland.
Earthing:
- Dedicated earth conductor required.
- Earth continuity must be maintained from mains supply to motor frame.
- Supplementary earth bond between motor body and mill frame required.
- Earth resistance: Less than 1 ohm.
Isolation:
- Lockable isolating switch must be installed adjacent to machine, visible from starter position.
- Switch rating: Minimum 20 A.
Protection:
- Thermal overload relay correctly set to 15.6 A (motor nameplate FLA).
- Short circuit protection via MCB or fuse rated 20 A, Type C or as advised by starter manufacturer.
All electrical work shall be performed by licensed electricians in compliance with local regulations.
First Start-Up Checklist
Before starting, verify the following:
Mechanical:
- ☐ Foundation bolts torqued.
- ☐ Rotor turns freely by hand; no contact between rotating and stationary parts.
- ☐ All wear parts installed correctly and secure.
- ☐ Screen properly fitted; output chute sealed.
- ☐ Belts installed and tensioned.
- ☐ Belt guards fitted and fastened.
- ☐ All access covers and inspection doors closed and secured.
- ☐ Feeder empty and clear of obstructions.
- ☐ Plummer block bearings greased.
Electrical:
- ☐ Motor winding insulation test passed (>1 MΩ).
- ☐ Supply voltage matches motor nameplate.
- ☐ Earthing continuity verified.
- ☐ Starter connections checked and torqued.
- ☐ Overload relay set to 15.6 A.
- ☐ Emergency stop tested for function.
- ☐ Key switch in operator’s possession; starter in “off” position.
Water (if operating wet):
- ☐ Water supply connected and pressurised.
- ☐ Flow control valve accessible.
- ☐ Drainage path clear.
Run-in procedure:
Dry run (no load, no water):
- Start motor; observe rotation direction (arrow marked on mill cover).
- If incorrect, isolate supply and swap any two phases at starter.
- Run for 5 minutes; listen for unusual noise, check vibration, monitor bearing temperatures.
- Stop; check belt tension and bolt torque.
Wet run (water only, no feed):
- Start water flow at 500 L/hr.
- Start mill.
- Confirm water flows through screen and discharge sluice without leakage.
- Check for misting or spray from seals; adjust water rate if required.
Load introduction:
- Begin feeding clean, sized rock (half-inch minus) at approximately 1 tonne per hour.
- Gradually increase to full rated feed rate over 30 minutes.
- Monitor motor amperage; do not exceed 15.6 A.
- Observe product discharge; verify particle size passing screen.
Commissioning sign-off:
- ☐ Machine operates smoothly across feed range.
- ☐ No abnormal vibration or noise.
- ☐ Belt tension stable.
- ☐ Motor current within limits.
- ☐ Operator trained on basic controls and emergency stop.
- ☐ Installation checklist completed and filed.
Date: Installed by: Verified by: ______________
12. Daily Operator Checks
Pre-Start Inspection
Before starting the SYOGM Rothensteed Mill each shift, the operator shall verify the following:
Guards and Covers:
- ☐ All belt guards securely fastened – do not operate with guards removed.
- ☐ Rotor access covers closed and latched.
- ☐ Feeder inlet cover in place (if conveyor not yet installed).
- ☐ Discharge chute screen access door secured.
Obstructions and Foreign Material:
- ☐ Feeder hopper clear of rocks, trash, or buildup from previous shift.
- ☐ Rotor free to turn – manually rotate using external pulley or barring slot; minimum one full revolution, no contact.
- ☐ Discharge chute and sluice entry clear of packed material.
- ☐ Screen surface free of lodged tramp material.
Belt Condition:
- ☐ Visually inspect all three Type A V-belts:
- No fraying, cracking, or glazing on sidewalls.
- No separation of cord layers.
- Belts sit correctly in pulley grooves – not bottomed out or riding high.
- ☐ Belt tension check:
- Press thumb firmly at belt mid-span; deflection should be 10–12 mm.
- Belts should not squeal on start-up.
Fasteners:
- ☐ Visual check of motor mounting bolts and slide rail locks.
- ☐ Plummer block bearing housing bolts – confirm no loosening.
- ☐ Feeder attachment bolts – secure.
Water Supply (wet operation only):
- ☐ Water supply valve open; pressure gauge reading normal.
- ☐ Hose connections leak-free.
- ☐ No blockage at water inlet point on feeder.
Work Area:
- ☐ Floor area clear of tools, debris, or spillage.
- ☐ Emergency stop accessible and unobstructed.
- ☐ Adequate lighting for safe operation.
Documentation:
- ☐ Previous shift log reviewed for noted issues or maintenance actions.
If any deficiency is identified, do not start the machine. Report to supervisor and rectify before operation.
Monitoring Motor Amperage During Operation
Motor current is the primary indicator of mill loading and must be observed continuously during operation.
Procedure:
Observe ammeter at starter enclosure during:
- Start-up (brief inrush current expected).
- Steady-state operation.
- Feed rate changes.
Normal operating range:
| Parameter | Value |
|---|---|
| Motor nameplate FLA | 15.6 A |
| Recommended continuous operating range | 70–90% of FLA (10.9–14.0 A) |
| Maximum continuous | 100% FLA (15.6 A) – do not exceed |
| Overload trip setting | 15.6 A (class 10 or 20) |
- Operator actions based on amperage reading:
| Amperage | Condition | Action Required |
|---|---|---|
| Below 10.0 A | Underloaded | Increase feed rate gradually to improve efficiency. |
| 10.9–14.0 A | Optimal | Maintain current feed rate. |
| 14.0–15.6 A | High load | Monitor closely; reduce feed rate if sustained. |
| Above 15.6 A | Overload | Immediately stop feed; reduce feed rate; if persists >5 seconds, stop mill and investigate. |
Log ammeter reading at start of shift, mid-shift, and end of shift in operator logbook.
Erratic ammeter movement:
- Fluctuating needle indicates uneven feed rate.
- Steady climb indicates screen blinding or material buildup.
- Sudden drop may indicate belt slippage or feed interruption.
Never leave a running mill unattended without ammeter observation capability.
Checking for Unusual Noise or Vibration
The trained operator’s critical diagnostic tools are hearing and touch. Stop and investigate if any of the following are detected:
Noise:
| Sound | Likely Cause | Action |
|---|---|---|
| Squealing | Belt slippage | Stop; re-tension belts. |
| Rhythmic tapping | Loose impact plate or foreign object | Stop immediately; inspect rotor and static plates. |
| Grinding or scraping | Rotor contacting stationary parts | Stop immediately; check wear part clearance. |
| Rumbling | Worn bearings | Stop; check Plummer blocks for heat/play. |
| Popping | Material backing up at feeder | Clear obstruction; reduce feed rate. |
| High-pitched whine | Over-tensioned belts or motor bearing issue | Check tension; listen at motor bearings. |
Vibration:
- Normal: Smooth operation; hand on frame feels steady hum.
- Abnormal: Visible shaking of feeder, covers, or discharge chute.
Procedure if abnormal vibration detected:
- Stop feed immediately.
- Allow mill to run empty (30–60 seconds).
- If vibration ceases with load removed: Feed-related imbalance – check for tramp metal, oversized feed, or uneven distribution.
- If vibration continues empty: Mechanical issue – stop mill, lock out power, inspect:
- Buildup on rotor faces.
- Missing or broken impact plates.
- Loose Plummer block bolts.
- Worn belts causing uneven pulley loading.
Record all noise and vibration events in operator logbook.
Screen Condition and Cleanliness
The output screen directly controls product particle size and mill capacity. A compromised screen renders the mill ineffective.
Inspection Frequency:
- Visual check: Hourly during operation.
- Hands-on check: Daily at shift end or during cleaning.
What to look for:
Tears or holes:
- Allows oversize particles to pass.
- Action: Replace screen immediately.
Blinding (plugged apertures):
- Fine, damp material wedged in screen mesh.
- Indicators: Reduced throughput, elevated motor amperage, clean oversize in product.
- Action:
- Stop mill; flush screen with pressure washer from underside.
- If wet operation: Increase water flow rate.
- If persistent: Screen may require replacement with anti-blinding type or larger opening.
Wear thinning:
- Screen wire visibly worn, especially at impact zone.
- Action: Replace during next scheduled maintenance; monitor closely.
Loose fit or bypass:
- Material escaping around screen edges.
- Action: Re-seat screen; check gasket condition; tighten retainers.
Screen Cleaning Procedure:
- During operation (wet): Maintain adequate water flow; check that spray (if fitted) is directed at screen back face.
- End of shift:
- Stop mill and isolate power.
- Remove discharge chute access cover.
- Use pressure washer to clean screen from underside upward to dislodge lodged particles.
- Inspect screen surface with torch; reflect light through apertures to confirm openness.
- Reassemble before next start-up.
Screen Life Log:
- Record installation date.
- Record total operational hours at replacement.
- Note cause of replacement (wear / tear / blinding).
13. Lubrication Schedule
Plummer Block Bearings (2 off)
- Type: Split pedestal bearings with grease nipples.
- Lubricant: High-quality lithium-based EP grease, NLGI grade 2.
- Frequency:
- Daily: 2–3 strokes of manual grease gun per bearing before start-up.
- Weekly: Inspect for grease purge at seals; clean away excess.
- Caution: Over-greasing causes seal damage and overheating. Do not exceed 3 strokes daily unless bearing runs hot or in dusty conditions.
Motor Bearings
- Type: Sealed for life – no field lubrication required.
- Action: Listen for noise; replace motor if bearings fail.
Feeder Hinge Points (if fitted)
- Frequency: Weekly.
- Lubricant: Light machine oil or lithium grease.
- Points: Pivot shafts, linkage pins.
Belt Tensioning Slide Rails
- Frequency: Monthly.
- Lubricant: Anti-seize compound or light grease on threads.
- Purpose: Prevent corrosion and ensure adjustability.
Note: Keep a grease gun dedicated to this machine and stored clean. Contaminated grease destroys bearings.
14. Troubleshooting Guide
| Problem | Probable Cause | Corrective Action |
|---|---|---|
| Mill will not start | No power supply | Check isolator; reset tripped breaker |
| Emergency stop engaged | Twist to release; reset | |
| Overload relay tripped | Allow cooling; reset; investigate cause | |
| Key switch off | Insert key; turn to ON position | |
| Motor fault | Check connections; test motor insulation | |
| Low capacity / throughput | Feed rate too low | Increase gradually; monitor amperage |
| Screen blinded | Clean or replace screen | |
| Worn impact plates | Inspect; replace wear parts | |
| Belt slippage | Re-tension belts | |
| Insufficient water flow | Increase to 1000 L/hr | |
| Feed too coarse | Ensure <½" feed size | |
| Oversize in product | Screen torn or holed | Replace screen |
| Screen bypass | Re-seat screen; replace gasket | |
| Incorrect screen fitted | Verify mesh size; install correct screen | |
| Motor overload / high amperage | Excessive feed rate | Reduce feed immediately |
| Screen blinded | Clean screen | |
| Material buildup inside mill | Stop; clean mill interior | |
| Belt tension too high | Slightly reduce tension | |
| Mechanical binding | Check rotor clearance; inspect bearings | |
| Excessive vibration | Unbalanced rotor | Clean buildup from rotor faces |
| Worn or missing impact plates | Replace worn plates | |
| Loose Plummer block bolts | Tighten to torque | |
| Worn bearings | Replace Plummer block bearings | |
| Foreign object inside mill | Stop; remove object; inspect for damage | |
| Belt squealing / slipping | Insufficient tension | Re-tension belts |
| Belts glazed or worn | Replace belts | |
| Oil or grease on belts | Clean pulleys; replace belts | |
| Overloaded mill | Reduce feed rate | |
| Bearing overheating | Insufficient lubrication | Grease bearings (2–3 strokes) |
| Over-greasing | Clean excess grease; reduce strokes | |
| Misalignment | Check pulley alignment | |
| Belt tension too high | Reduce tension slightly | |
| Bearing worn or damaged | Replace bearing | |
| Material backing up at feeder | Feed rate too high | Reduce feed rate |
| Screen blinded | Clean screen | |
| Discharge chute blocked | Clear obstruction | |
| Water flow insufficient | Increase water rate | |
| Erratic ammeter reading | Uneven feed rate | Stabilize feed; check conveyor |
| Intermittent belt slip | Check tension; inspect belts | |
| Electrical fault | Check connections; consult electrician | |
| Dust emission (dry mode) | Enclosure not sealed | Check covers; seal leaks |
| Excessive air movement | Reduce airflow; improve shrouding | |
| Dry operation without dust control | Convert to wet mode or install extraction |
15. Maintenance Schedule
Daily (Every Shift)
- ☐ Pre-start inspection per Section 12.
- ☐ Grease Plummer block bearings (2–3 strokes).
- ☐ Monitor motor amperage throughout shift.
- ☐ Check belt condition and tension.
- ☐ Inspect screen for blinding, tears, or wear.
- ☐ Clean screen with pressure washer at shift end (wet operation).
- ☐ Record observations in operator logbook.
- ☐ Run mill empty; isolate power; secure key.
Weekly
- ☐ Inspect all wear parts (16 static liners, 3 impact plates).
- ☐ Measure and record wear thickness (if applicable).
- ☐ Check Plummer block bearing temperature during operation (hand test: <60°C).
- ☐ Inspect grease purge; clean excess.
- ☐ Lubricate feeder hinge points.
- ☐ Check all fasteners for loosening; torque as required.
- ☐ Inspect electrical cables and glands for damage.
- ☐ Test emergency stop function.
Monthly
- ☐ Replace wear parts if worn beyond acceptable limit.
- ☐ Inspect pulleys for groove wear or damage.
- ☐ Lubricate belt tensioning slide rail threads.
- ☐ Check rotor clearance; adjust if necessary.
- ☐ Inspect motor cooling fan and air intake; clean if obstructed.
- ☐ Verify overload relay setting (15.6 A).
- ☐ Test earth continuity.
Quarterly (3 Months)
- ☐ Replace standard wear parts (per supplied kit).
- ☐ Replace V-belts (Type A) if showing signs of wear.
- ☐ Inspect and regrease motor bearings (if non-sealed type; consult motor manual).
- ☐ Complete mill interior inspection:
- Remove covers; inspect rotor and static plates.
- Check for cracks, distortion, or uneven wear.
- Clean accumulated fines from mill housing.
- ☐ Check alignment between motor and mill pulleys; realign if required.
Annually
- ☐ Replace Plummer block bearings (preventative).
- ☐ Inspect rotor shaft for wear or damage.
- ☐ Complete motor insulation test.
- ☐ Full electrical inspection by licensed electrician.
- ☐ Repaint or touch up corrosion-damaged surfaces.
- ☐ Comprehensive structural inspection of stand and frame.
16. Storage and Decommissioning
Short-Term Storage (Up to 1 Month)
- Run mill empty to clear all material.
- Operate with water only for 5 minutes (wet mode) to flush system.
- Stop mill; isolate power; remove key.
- Clean exterior surfaces; remove accumulated dust and fines.
- Grease Plummer block bearings (3 strokes).
- Cover mill with breathable dust cover.
- Store in dry, sheltered area.
Long-Term Storage (More than 1 Month)
- Complete all short-term storage steps.
- Remove belts; store in cool, dark location away from direct sunlight.
- Apply light oil or rust preventative to:
- Unpainted metal surfaces.
- Pulley grooves.
- Rotor shaft exposed areas.
- Grease Plummer block bearings thoroughly until fresh grease purges from seals.
- Seal all openings (feeder inlet, discharge chute) to prevent rodent entry.
- Wrap motor with plastic; include desiccant bag inside wrapping.
- Rotate rotor by hand monthly to redistribute lubrication.
- Inspect quarterly for corrosion or pest intrusion.
Decommissioning
- Isolate and lock out all power sources.
- Disconnect electrical supply; remove cables.
- Drain and disconnect water supply.
- Remove belts and store (if reusable) or dispose.
- Remove motor; store or dispose per local regulations.
- Dismantle mill into major assemblies:
- Stand
- Main milling assembly
- Feeder
- Discharge chute
- Segregate components by material type for recycling.
- Dispose of wear parts, bearings, and electrical components per local environmental regulations.
- Paint or label “DECOMMISSIONED – NOT FOR OPERATION” on main frame if retained on site.
17. Technical Specifications
| Parameter | Specification |
|---|---|
| Model | SYOGM Rothensteed Mill |
| Intended feed size | ≤ ½ inch (12.7 mm) |
| Typical product size | Passing 1.5 mm screen (adjustable) |
| Capacity | 3–5 tonnes per hour (dependent on feed and screen) |
| Motor power | 10 HP (7.5 kW) |
| Motor speed | 1440 RPM |
| Motor current (FLA) | 15.6 A at 415 V, 50 Hz |
| Motor protection | Thermal overload relay set to 15.6 A |
| Power transmission | 3 × Type A V-belts |
| Rotor speed | Approximately 900–1000 RPM (driven) |
| Impact plates | 16 static + 3 rotating (manganese-enhanced) |
| Bearings | Plummer block split-type (2 off) |
| Water consumption | Recommended: 1000 L/hr; Minimum: 500 L/hr |
| Screen options | 1.5 mm (standard), 3/8", 30 mesh, others available |
| Machine weight (without motor) | Approximately 850 kg |
| Total installed weight | Approximately 950 kg |
| Dimensions (L × W × H) | 1800 mm × 1200 mm × 1600 mm (approximate) |
| Foundation type | Reinforced concrete, 150 mm min thickness |
18. Spare Parts List
| Part Number | Description | Quantity per Machine | Recommended Stock Level |
|---|---|---|---|
| SY-WP-001 | Static wear liner (set of 16) | 1 set | 2 sets |
| SY-WP-002 | Static impact plate (manganese) | 3 | 6 |
| SY-BL-001 | Type A V-belt | 3 | 6 |
| SY-BL-002 | Type B V-belt (wear parts kit) | 3 | 3 |
| SY-SC-001 | Screen – 1.5 mm | 1 | 3 |
| SY-SC-002 | Screen – 3/8" | 1 | 1 |
| SY-SC-003 | Screen – 30 mesh | 1 | 1 |
| SY-BR-001 | Plummer block bearing assembly | 2 | 2 |
| SY-FT-001 | Feeder hinge pin | 2 | 2 |
| SY-GS-001 | Discharge chute gasket | 1 | 2 |
| SY-KT-001 | 3-month wear parts kit (liners + plates + belts) | 1 kit | 1 kit |
Ordering Information:
Contact SYOGM Parts Department with machine serial number and part number. Emergency orders: Specify “URGENT” on purchase order.
19. Operator Log Sheet
Daily Operator Log
Machine Serial Number:
Date: Shift: Day / Night Operator: ______________
| Check Item | Status (OK / Not OK) | Remarks / Action Taken |
|---|---|---|
| Pre-Start Checks | ||
| Guards and covers secure | ||
| Rotor free to turn | ||
| Belts condition and tension | ||
| Screen condition | ||
| Feeder clear | ||
| Water supply (wet mode) | ||
| Work area clear | ||
| Operational Data | ||
| Start-up amperage (A) | ||
| Mid-shift amperage (A) | ||
| End-shift amperage (A) | ||
| Water flow rate (L/hr) | ||
| Feed rate estimate (tph) | ||
| Observations | ||
| Unusual noise? (Y/N) | ||
| Unusual vibration? (Y/N) | ||
| Screen blinded? (Y/N) | ||
| Belt slippage? (Y/N) | ||
| End of Shift | ||
| Mill run empty | ||
| Screen cleaned | ||
| Power isolated | ||
| Key returned | ||
| Area swept clean |
Supervisor Review: Date:
Document Control
Manual Title: Manual of Operation for the SYOGM Rothensteed Mill
Document Number: SYOGM-OM-2026-01
Revision: 1.0
Date of Issue: 12 February 2026
Prepared by: SYOGM Technical Publications
Approved by: ____________________
Important Notice:
The information contained in this manual is accurate at the time of publication. SYOGM reserves the right to improve, modify, or change specifications and components without notice and without incurring obligation to previously supplied units.
Copyright:
© 2026 Start Your Own Gold Mine. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”
END OF MANUAL