If you are building or upgrading an alluvial gold plant, the shaking table is usually the last piece of equipment that decides how clean your concentrate is — and how much you lose to the tailings. It sits at the end of the gravity circuit, after the trommel scrubber, the screen and the centrifugal concentrator, and its job is simple to describe but hard to do well: separate gold from heavy sand using nothing but water, a riffled deck and a slight sideways shake.
This guide covers what actually determines whether a shaking table works on your ore, and how to specify one without over- or under-buying.
What a shaking table actually does
A shaking table is a gravity concentrator. Slurry is fed across a slightly tilted, riffled deck that is shaken along its long axis. Three things separate the particles at the same time:
- Density difference — gold (specific gravity around 19) settles into the riffles while quartz and sand (around 2.6) wash over them.
- Particle size — finer particles travel further than coarse ones under the same water flow.
- Water film — the cross-flow of wash water carries the light material off the lower edge while heavy minerals stay trapped.
Because the table works on density and size, the size range you feed it matters enormously. This is the single most common source of disappointment with shaking tables.
Step 1: Match the deck type to your feed size
Shaking tables are built with different riffle profiles for different size bands. A 6S-type table is normally supplied in three deck variants:
| Deck type | Typical feed size | Use it when |
|---|---|---|
| Coarse sand deck | Roughly 0.5–2 mm | Concentrate from a jig or rougher table, coarse alluvial gravel fractions |
| Fine sand deck | Roughly 0.074–0.5 mm | The most common choice — typical alluvial sand after screening |
| Slime deck | Below roughly 0.074 mm | Fine material recovered from settling ponds, overflow and tailings |
If you feed a deck material it was not designed for, you lose gold. Feeding coarse sand to a slime deck overloads the riffles and flushes gold out with the tailings. Feeding slime to a coarse deck gives you almost no recovery, because the fine particles simply wash across the riffles without settling.
The practical rule: classify before you tabulate. Screen the feed into at least two size bands and run each band on the correct deck, or accept a lower recovery.
Step 2: Work out how many decks you need
A single deck handles a modest throughput. Producers who need to process a continuous concentrate stream usually run several decks in parallel rather than one large table, because the separation quality depends on a thin, evenly distributed bed of material — you cannot simply scale a table up by making it wider.
To size the circuit, you need three numbers:
- Your concentrate feed rate in t/h entering the table circuit (not your total plant feed — the table only sees the concentrate from the upstream rougher stage).
- The size distribution of that concentrate, so you can allocate decks correctly.
- Your target concentrate grade, which determines how many cleaning passes you need.
A typical arrangement is a rougher table followed by one or two cleaner tables, with the cleaner tailings returned to the rougher feed. This middlings recirculation is what turns a mediocre recovery into a good one.
Step 3: Check your water supply before you order
Shaking tables are thirsty. They use wash water continuously across the deck, and the flow rate has to be adjustable, because the correct wash water setting changes with feed size, feed rate and grade.
If your site has limited water, plan for:
- A settling pond and return pump, so the wash water is recirculated rather than lost.
- A head tank with a constant level, feeding the table through an adjustable valve. Gravity-fed wash water with a stable head is far easier to control than a pump running at variable pressure.
- Consistent feed density. A slurry that surges thick and thin will ruin the separation no matter how well the table is adjusted.
Where the table fits in the alluvial flowsheet
A well-designed alluvial plant recovers gold in stages, with each stage handling a narrower size band and a higher grade:
- Trommel scrubber and screen — breaks up clay and separates the gravel from the sand. Washing quality here decides how much fine gold is available for recovery downstream.
- Centrifugal concentrator — takes the screened undersize and recovers a large share of the free gold, including fine particles, at high upgrade ratios.
- Shaking table — cleans the concentrator product and gives you a final gravity concentrate that is low in volume and ready for smelting or further upgrading.
If you are not yet recovering the fine fraction of your feed, the table is not the first thing to fix — the washing and screening stage is. See the equipment options on our alluvial gold equipment page and our trommel and washing systems page.
Common mistakes that cost recovery
- Feeding unclassified material. The most frequent error. One table cannot separate 3 mm gravel and 30 micron slime at the same time.
- Uneven feed. A fluctuating slurry density changes the bed depth on the deck and destroys the separation. Use a steady head tank, not a direct pump from a pit.
- Running too fast to chase tonnage. Increasing the stroke or feed rate beyond the deck’s capacity looks productive and loses gold. Recovery on a table is inversely related to throughput.
- Ignoring wash water adjustment. The wash water valve is a control, not a setting. It needs adjusting as feed grade changes.
- Skipping the cleaning pass. A rougher-only table typically produces a concentrate that still needs smelting or a second pass to be saleable.
Maintenance that actually matters
Shaking tables have very few wearing parts, but the parts that do wear directly affect recovery:
- Riffles and deck surface — worn or bent riffles change the flow pattern. Inspect and replace as a set.
- Head motion bearings — the eccentric drive needs clean lubrication and a check for play. Excess play shows up as inconsistent stroke.
- Deck support — the deck must sit level side to side and at a consistent slope end to end. A knocked support changes the tilt and the separation.
What to tell a supplier before you buy
If you send a supplier the following, they can size the table circuit correctly on the first attempt instead of guessing:
- Feed size distribution of the material entering the table (sieve analysis if you have it).
- Feed rate in t/h and slurry density.
- Grade of the feed and the grade you need in the concentrate.
- Available wash water flow rate, and whether it can be recirculated.
- Site conditions: power supply, floor area, ambient temperature if it freezes.
If you are not yet sure what your concentrate grade will be, a small lab-scale gravity test is worth doing before committing to a full-size circuit — see our laboratory equipment page.
If you already know your feed and target, send us the numbers and we will recommend the deck types, the number of units and the flowsheet around them. Send us your ore data here and our engineers will come back with a configuration.