Carbide buttons, mining bits and road-milling teeth

Carbide buttons are the small domed, conical or chisel-shaped slugs of tungsten carbide set into the face of a rock bit. They do the breaking; the steel around them holds them.

ITIA, the International Tungsten Industry Association, names tunnelling and road milling as the main construction uses, with hardmetal “rock drills and road chisels to remove old tarmac” as the typical products. Its longer list adds asphalt reclamation, tunnel boring and surface mining.

• Button bits for top-hammer and down-the-hole drilling, worn or broken, buttons still in the face.
• Loose buttons that fell out of worn bits or sat in a bin as spares.
• Roller cone bits. ITIA's labeled figure of one shows carbide buttons, carbide inserts and a tungsten-bearing hardfacing layer.
• Road-milling teeth (picks or conical bits) from cold planers: a carbide tip on a steel body that fits a holder on the milling drum.
• Trencher, rock saw and auger teeth with carbide tips.

Mining and construction grades are usually coarse, with tungsten carbide grains up to 20 microns and 6 to 10% cobalt, according to ITIA. ITIA says these jobs need impact resistance, abrasion resistance and high fracture toughness: the carbide brings the hardness, the cobalt the toughness.

Sources: ITIA, Cemented carbides (newsletter excerpt, June 2010); ITIA, Applications and markets; ITIA, Recycling of tungsten, part 1 (May 2018).

On a button bit, the carbide is the set of dull gray buttons standing proud of the face. The skirt, shank and splines behind them are steel. On a road tooth, the carbide is the small tip at the point, with the steel body and shank behind it.

Weight gives loose buttons away. Measured carbide grades run about 13 to 15 g/cm3, while NIST lists iron at 7.874, so a loose button weighs roughly twice what an iron slug of the same size would.

A magnet is no help with whole bits, because the steel body grabs it whatever the tip is made of. Our guide on whether carbide is magnetic covers loose pieces.

Diamond cutters on modern drill heads are a polycrystalline diamond layer sintered onto a tungsten carbide substrate, per ITIA. Bag them apart from plain buttons.

Sources: OSTI, cemented tungsten carbide grades (2023 manuscript); OSTI/ORNL, WC-Co part study (2019 manuscript); NIST, X-ray mass attenuation coefficients, Table 1 (densities); ITIA, Cemented carbides (newsletter excerpt, June 2010).

Arizona and Nevada are mining states. In its Mineral Commodity Summaries 2026, USGS ranked Nevada first and Arizona second among the states by nonfuel mineral production value in 2025. The same edition puts Arizona at about 70% of US copper output that year and Nevada at about 64% of US gold.

That edition also estimates that 60% of the tungsten consumed in the US in 2025 went into cemented carbide parts, mainly for construction, metalworking, mining and oil and gas drilling.

We pick up in every city in Arizona, Nevada and California. We pay cash where state law allows, and each state writes its own payment rules:

• Arizona: a scrap metal transaction of $300 or more may not be paid on site. Payment is a check or money order mailed to the address on the seller's driver license or other listed ID. The rule goes by dollar amount, not by metal, and it does not apply to industrial accounts that preregister their authorized sellers each year.
• Nevada: a scrap metal processor pays for a purchase of $150 or more only by check or electronic transfer. The statute's definition of scrap metal does not name carbide or tungsten.
• California: the rule that pays by mailed check, or on or after the third business day, covers only copper, copper alloys, stainless steel and aluminum. Carbide and tungsten are not on that list; the record and ID rules cover scrap metal purchases in general.

The scrap metal rules guide covers the ID, records and holding periods in all three states.

Sources: USGS, Mineral Commodity Summaries 2026; USGS, MCS 2026: Copper; USGS, MCS 2026: Gold; USGS, MCS 2026: Tungsten; Arizona Revised Statutes 44-1642; Nevada Revised Statutes chapter 647; Arizona Revised Statutes 44-1641 (definitions); California AB 1508, Chapter 531, Statutes of 2012 (Bus. & Prof. Code 21608.5); California Attorney General, Information Bulletin 2025-DLE-12.