Tungsten Carbide Scrap Specification — Mixed Hard Carbide (WC-Co)

Mixed hard carbide describes sintered cemented carbide arisings that have not been separated into single-application streams. The material is a composite: tungsten carbide (WC) grains cemented by a metallic binder — most commonly cobalt, sometimes nickel, and in some corrosion-resistant grades a nickel-chromium binder. Because it is a sintered composite rather than an alloy, it cannot be characterised by a single alloy designation the way a stainless or aluminium grade can.

A mixed lot typically arrives from a collector who has aggregated carbide from several generators: a machine shop's insert bin, a tool room's ground-out rejects, a maintenance department's worn wear parts, and occasionally offcuts from a carbide stockist. The pieces are chemically related but metallurgically diverse. Binder fraction, additional cubic carbides (titanium, tantalum, niobium), grain size and coating type all vary between pieces in the same drum.

The consequence for procurement is straightforward: mixed hard carbide is priced and processed as a mixed lot, not as a grade. Where a processor needs a narrow input window, they either sort the lot themselves after arrival or buy a segregated stream instead. Segregated streams — cutting tools, mining and wear, soft scrap — are documented separately on their own specification pages, and a mixed offer that can be broken into those streams is usually worth breaking.

Nautica handles mixed hard carbide as a trading stream out of the Netherlands. Where this document describes handling, packing and documentation, it describes our commercial practice. Where it describes metallurgy or processor behaviour, it describes general industry practice and not a promise attached to a particular cargo.

Mixed hard carbide is a physical-condition category rather than a shape category. In practice a lot will contain several of the following, in proportions that vary by source:

Field identification of cemented carbide relies on a small number of consistent physical behaviours. Carbide is markedly denser than steel of the same size, so a small piece feels disproportionately heavy in the hand. It is extremely hard and brittle: it chips or shatters rather than bending, and a file will not bite into it. Most sintered carbide is weakly magnetic because of the cobalt binder, which distinguishes it from non-magnetic pieces but does not separate it from steel — steel is strongly magnetic and softer, and a file test resolves the difference quickly.

The identification errors that matter commercially in a mixed lot are the ones that add weight without adding recoverable carbide. High speed steel tooling is the most frequent: an HSS end mill and a solid carbide end mill can look identical after use, but HSS is noticeably lighter, will spark freely on a grinding wheel and can be marked with a file. Brazed tooling is the second: the carbide tip may be a small fraction of the piece weight, with the steel shank making up the rest.

Coatings do not change what the substrate is, but they change what a surface instrument reads. Titanium nitride, titanium aluminium nitride, aluminium oxide and diamond-like coatings all sit on top of the carbide and will be seen by a surface analytical reading before the substrate is.

Because tungsten carbide is not traded on a terminal exchange, there is no published settlement price to reference. Value discussion is built from the recoverable tungsten content a processor expects to obtain, the cost of the recovery route the material will take, the binder content that can be recovered alongside it, and the handling burden created by contamination and sorting.

For a mixed hard lot the dominant variables are these:

Deductions on mixed hard carbide are almost always weight-based rather than chemistry-based, because the practical problem is non-carbide mass travelling in the lot. Where deductions apply, the mechanism — visual estimate, physical sort, agreed sample sort, or analysis — must be written into the contract before shipment. There is no industry-default deduction table that applies automatically.

Carbide is dense, so packing is governed by weight limits long before volume limits. Overfilled containers and oversized single packages are the two most common causes of loading problems for this material. Steel drums and small strong bins on pallets are the normal presentation, kept to a weight a forklift and a receiving yard can handle safely.

Segregation discipline directly affects value. A lot presented as separately packed and labelled fractions — clean solid carbide in one set of drums, brazed and steel-attached items in another, fines and broken material in a third — allows a buyer to evaluate each fraction on its own merits rather than pricing the whole lot to the weakest part.

Mixed hard carbide moves in far less volume than a full container of bulk scrap because of its density; a modest number of drums can reach a container's payload limit. Weight verification before loading, correct distribution inside the container and accurate declared weights are therefore routine requirements rather than refinements.

Export and import of secondary raw materials is subject to waste-shipment and customs regimes that differ by origin, destination and material description. Documentation requirements, prior-notification obligations and importer licensing are determined by the specific trade lane and must be confirmed for each shipment. Our export process and Rotterdam port operations pages describe the sequence we follow; they do not replace the advice of the buyer's own customs broker.

Analysis on a mixed hard lot serves two different purposes and the two should not be confused. Screening exists to sort — to separate carbide from high speed steel, to identify nickel-bound pieces, and to flag anomalies before packing. Contractual analysis exists to establish an agreed figure, and it requires a sampling protocol both parties have accepted in writing.

For mixed lots, representative sampling is harder than for single-origin streams precisely because the lot is heterogeneous. Sampling should span drums, depth within drums and size fractions. Elements that are usually of interest include tungsten, cobalt, nickel, iron and chromium, with iron indicating steel carry-over and chromium and nickel pointing to steel or nickel-bound grades.

Customs classification for tungsten-bearing secondary material depends on the actual composition and physical form of the goods, on whether the material is solid scrap, powder, sludge or residue, on the destination country, and on how the competent authority in that jurisdiction interprets the material description.

A mixed hard carbide lot can present additional classification complexity where non-carbide items — steel shanks, holders or other tooling — travel with the carbide, because the description of the goods must reflect what is actually shipped.

Nautica does not assign a definitive tariff code in advance for this stream. Buyers and importers should confirm the applicable classification, duty treatment and any import licensing or waste-shipment obligation with their own customs broker or the competent customs authority for the destination before contracting.