600 Tons a Day in Chongqing: Inside a C&D Waste Sorting Plant

Key facts — Chongqing C&D waste sorting plant

Chongqing builds and rebuilds at a pace few cities can match. What follows that activity is considerably less photogenic: broken concrete and brick, offcut timber, gypsum board, cable offcuts, timber from packaging, plastic film, and the mixed debris that every demolition and refurbishment job leaves behind.

Unsorted, that mixture has almost no market value. It is too contaminated to feed a concrete batching plant directly, too variable for most recyclers to accept, and far too labour-intensive to pick by hand at 600 tonnes a day.

A 600-tonne-per-day C&D waste sorting plant recently commissioned by Qinglv Environment in Chongqing exists to close that gap. The plant reports 100% resource utilisation — meaning every fraction leaving the line has a destination, and nothing is consigned to landfill as residual waste.

What got there was not a new technology. It was correct machine selection, correct order of operations, and dust control treated as a design input rather than an afterthought. This is a walk through the line in the sequence material actually travels, followed by the questions buyers most often raise at this capacity.

Start with composition, not with a machine list

The most common specification mistake in this sector is buying equipment before analysing the feedstock. A line designed for clean demolition rubble will fail on renovation waste, because renovation (decoration) waste carries a different mix: more timber, more gypsum board, more bagged material, more film plastic, and considerably higher variability from one truck to the next.

Chongqing's plant takes both streams. That decision drives everything downstream — it is the reason a bag opener sits near the front of the line rather than being treated as an optional extra, and the reason two different screening technologies appear in the same layout.

A useful rule: before any line is configured, run at least three grab samples across different weeks, size-fraction them by hand, and weigh the fractions. Ten thousand dollars of sampling saves a million dollars of retrofit.

How does a 600 t/day C&D waste sorting plant work?

In one sentence: the line progressively removes one material at a time, starting with the dirtiest and heaviest fractions and finishing with optical sorting on a cleaned, aerodynamically separated stream. Each step produces a narrower input for the next.

Step 1 — Bag breaking: dealing with waste that arrives in bags

Renovation waste in particular arrives bagged. Screening equipment cannot sort what it cannot see, and a sealed bag behaves like a single large contaminant — it rides the line intact and takes its contents with it to the wrong end of the plant.

The bag breaker machine solves this mechanically: rotating shafts with profiled blades tear the bags open and liberate the contents, without shredding or reducing the material inside. Correct blade-to-counter-blade clearance is what makes this work — too tight and you start processing the contents, too loose and bags pass through intact.

Specifying note worth carrying into any tender: ask for the bag opening rate as a measurable acceptance criterion, not a marketing claim. Ninety-percent and ninety-eight-percent bagging rates look similar on a brochure and very different on a conveyer belt after six months.

Step 2 —Trommel screen: primary sizing that keeps working when the feed turns ugly

A trommel screen is a rotating cylindrical drum, perforated with sized apertures and set at a slight incline. Material is fed into the upper end; as the drum rotates, the load is lifted and cascades across the perforated wall. Particles smaller than the aperture fall through and are collected underneath; everything larger travels the length of the drum and discharges at the far end.

On a C&D line this simple mechanism earns its position for three reasons. First, tolerance: concrete lumps, rebar offcuts and tangled film that would blind a vibrating deck in minutes simply pass through a rotating drum. Second, self-cleaning: the tumbling action, combined with scraper brushes on the drum surface, keeps the apertures open even when the feed is wet and clay-rich — the exact condition that shuts down conventional screens. Third, containment: a fully enclosed drum doubles as a dust housing, which matters given how much fine cement powder a demolition stream carries.

Two specification decisions shape the result. Aperture size sets the split point — commonly somewhere between 40 and 80 mm on a C&D line — and every downstream machine inherits that decision, so it should follow from the composition analysis rather than from whatever drum happens to be in stock. Drum speed is the other: running at roughly 25–40% of critical speed keeps the material cascading across the wall instead of riding the lifters, which is the difference between screening and merely transporting.

What a trommel cannot do is separate by shape. Within a single size fraction, a flat plank offcut and a fist-sized lump of concrete behave identically. Sorting those apart is the next machine's job.

Step 3 — 3D sorter: separating by shape, not by size

A 3D sorter — also called a bouncing screen or 3D separation deck — solves the problem size screening cannot touch. Material is fed onto an angled, elastic deck that accelerates and throws the load upward. Flat, stiff, two-dimensional items — plank offcuts, board, cardboard, folded film — bounce, land flat and travel up the deck. Compact, three-dimensional material — brick, concrete, stone, soil clods — rolls back down under gravity. One pass, two streams, separated by geometry rather than by size or weight.

This matters because C&D and renovation waste is where 2D and 3D material mix most aggressively. A single renovation load can carry plasterboard sheets, timber offcuts, cardboard packaging and film wrap — all flat — sitting on top of brick and concrete — all compact. Left together, the flat fraction contaminates the recycled aggregate while the compact fraction drags down the fuel output. Separated, each stream has a clean destination: the 3D fraction goes to crushing and aggregate production, the 2D fraction goes to wood recovery or RDF.

Three things decide whether a 3D sorter earns its keep on your material:

• Moisture behaviour. Wet cardboard bounces differently from dry. Ask for separation efficiency measured at your moisture range, not at the test rig's.

• Deck adjustability. Deck angle and throw need to be tunable on site, because the 2D-to-3D ratio in renovation waste shifts from one district to the next.

• Position in the line. A 3D sorter works best on a pre-sized fraction — fed directly after the trommel, where every particle already sits within a workable size band. Fed raw, it spends its energy re-sorting what the trommel should have handled first.

Step 4 — Ferrous and non-ferrous metals

C&D waste carries steel from every direction: rebar in concrete, nails and screws in timber, strapping, brackets, conduit. An overband or drum magnetic separator suspended over the belt removes it, and it is typically the single highest-revenue output tonne-for-tonne on a Chinese C&D line.

An eddy current separator then handles what magnets cannot: aluminium window profiles, copper cable offcuts, brass fittings. A rapidly rotating magnetic rotor induces eddy currents in non-ferrous particles and physically ejects them from the stream.

Specifying tips that matter more than logo selection:

• Recovery, not purity, is usually the right target here — downstream refining handles purity.

• Crushed or dirty aluminium is hard. If your stream includes window frames, size reduction upstream of the eddy current stage improves recovery sharply.

• Ask for performance figures at your actual belt loading and particle size range, not at catalogue conditions.

Step 5 — AI waste sorting and robotic picking

By this point the stream is clean, sized and metal-free — which is precisely what machine vision needs. This is where the Chongqing line departs from a conventional mechanical plant.

An AI optical sorter scans material on a fast-moving belt, classifies it by hyperspectral signature and shape, and ejects targeted items with jets of compressed air. On C&D waste the practical applications are separating specific polymers for recycling, removing PVC before RDF production (PVC contributes chlorine and therefore corrosion and dioxin risk downstream), and cleaning the wood fraction.

On the heavy-material picking platform, the plant deploys a high-payload robot rather than a human crew. This is the right deployment logic: the heavy fraction is where manual picking is slowest, most injury-prone and hardest to staff. The robot follows a preset programme, picks specific material consistently across shifts, and does not get tired at hour seven.

Two things determine whether this investment pays off, and neither is the robot:

• Presentation. A vision system can only classify what it can see. If material arrives overlapping or double-stacked, achievable purity drops regardless of the algorithm. Feed rate control upstream is part of the sorter's specification.

• Air quality. Dust on a camera lens is a sorting defect waiting to be billed. This is a direct, measurable argument for the dust control described below.

Why dust control decided whether this plant could operate at all

C&D waste generates dust continuously — concrete and cement fines at every impact point, gypsum powder from board breakage, and wood dust from screening. Plants that ignore it accumulate three expensive problems simultaneously.

1. Health and permitting. Respirable silica dust is a recognised occupational hazard. Enforcing agencies in most markets now expect documented control, and neighbours notice within a week.

2. Equipment life. Fine abrasive dust shortens bearing life, contaminates hydraulic systems and penetrates electrical enclosures. Maintenance cost is roughly proportional to how well you contain the dust.

3. Sorting accuracy. As noted above, dust degrades optical sensor performance. Plants often wonder why their AI sorter's purity drifts; the answer is frequently in the air, not the algorithm.

Chongqing's plant addresses it in two layers, which is worth copying:

At source. Every conveyor carries a customised dust module — an enclosed cover plus a drop tray at each transfer point. Containment at the point of generation is cheaper and more effective than collecting dust once it has dispersed.

At plant level. A negative-pressure water-mist spray system spans the building footprint. Negative pressure keeps contaminated air from migrating outward; the mist agglomerates fine particles so they settle instead of remaining airborne.

The two layers working together deliver what neither achieves alone, and the combined cost is a small fraction of the equipment it protects.

What does 100% resource utilisation actually mean?

It is worth being precise, because the phrase is used loosely across this industry.

In this context it means: every output fraction has a destination, and no residual material is landfilled. The plant's outputs would include recycled aggregate, ferrous scrap, non-ferrous scrap, wood, specified plastics, and light fraction going to refuse-derived fuel.

It does not mean every tonne becomes a high-value recycled product. Some fraction becomes fuel, and fuel is the lowest-value destination in the list. Anyone evaluating a supplier's "zero landfill" claim should ask one follow-up question: what percentage of output is sold as product versus burned as RDF? An honest supplier can answer immediately; the answer also tells you how well designed the front half of the line really is.

How much does a 600 t/day C&D waste sorting plant cost?

This is the question that matters commercially, and the honest answer depends more on your material than on the equipment catalogue.

As a rough screening reference only — and the spread is wide because configuration varies enormously — a 200–600 t/day C&D line built in China generally falls somewhere in the range of RMB 3-10 million for the equipment package, before civil works, installation, shipping and local compliance. Anyone quoting without having seen your composition data is guessing, whatever confidence they project.

The most effective way to convert that range into a usable number is not a longer questionnaire. It is a material test: send your stream, run it through the actual machines, and size the line from observed behaviour rather than assumptions.

Five things worth copying if you are specifying a C&D line

4. Analyse before configuring. Three grab samples across three different weeks will change your equipment list. Skipping this step is the single most expensive shortcut available.

5. Count transfer points, not machines. Every conveyor-to-conveyor transfer is a wear location, a dust source and a maintenance item. The Chongqing line's reported saving came from removing such transitions, not from cheaper components.

6. Design dust control in at concept stage. Retrofitting containment into a built plant costs several times more than including it initially and never performs as well.

7. Put robots where labour is worst. Deploy automation at injury-prone, hard-to-staff positions first, not where it photographs best.

8. Secure your outlets before you build your intake. A recycling line with no buyer for its products simply relocates the waste.

Frequently asked questions

What is C&D waste?

Construction and demolition waste is the material generated by building, demolition, renovation and civil works — concrete, brick, stone, timber, metals, gypsum board, glass, plastics and soil. In Chinese practice, "construction and decoration waste" additionally covers the renovation stream, which typically contains more timber, gypsum board, bagged material and film plastic.

How much waste does a 600 t/day plant handle per year?

At design capacity with roughly 300 operating days per year, a 600 t/day line processes approximately 180,000 tonnes annually. Real-world throughput depends on feedstock availability, maintenance scheduling and how often the line must be stopped to clear blockages.

What equipment is needed for a C&D waste sorting plant?

A minimum viable configuration includes receiving and metering, pre-screening (usually a star screen), a bag breaker if bagged material arrives, size classification (disc or flip flow screen), a shredder or crusher for oversize, air classification (wind shifter), magnetic separation, eddy current separation, and a picking station. AI optical sorting is added where output purity requirements justify it.

What is the difference between a star screen and a disc screen?

Both separate by size, but they suit different material. A star screen uses rotating shafts with star discs and tolerates large, awkward, mixed items such as rubble and long timber — it is usually the primary screen. A disc screen uses discs on shafts with adjustable spacing and offers finer control over cut size — usually applied to cleaner, dry, bulky material. Many plants run a star screen first and a disc screen downstream.

Can a C&D waste sorting plant achieve zero landfill?

Yes, and it is more achievable for C&D than for most municipal waste streams, because so much of it has established value: aggregate, metals and combustible light fraction for RDF. The practical requirement is that someone must take each output — which is why the sales side of the business has to be developed alongside the technical one.

How long does it take to build?

Depending on permitting and civil works, equipment delivery for a plant of this scale typically takes three to five months from contract, with installation and commissioning taking a further two to three months. Your situation may differ; treat this as a planning reference rather than a commitment.

Where can I see a C&D sorting line running?

Qinglv Environment operates commissionable reference plants in China, including the 600 t/day line described here, the Guangzhou and Shanghai C&D projects, and paper mill waste lines in Southeast Asia including Malaysia. Visiting a running line with your own material in hand settles more questions in one day than any proposal.

Want a line configured for your material?

Every plant described above was sized from an actual waste stream rather than from a template. If you are evaluating a C&D or renovation waste project, the most useful first step is a material test — send us your composition and target capacity, and you will receive a line layout, equipment list and budget range worked out from how your material actually behaves.

Qinglv Environment — turnkey C&D waste sorting plant design, equipment manufacture, installation and commissioning. 15+ years · 500+ lines · 90% of core components made in-house.