Slag in the context of Zinc

Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron, copper, silver, tin, lead, and zinc. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal behind. The reducing agent is commonly a fossil-fuel source of carbon, such as carbon monoxide from incomplete combustion of coke—or, in earlier times, of charcoal. The oxygen in the ore binds to carbon at high temperatures, as the chemical potential energy of the bonds in carbon dioxide (CO₂) is lower than that of the bonds in the ore.

Sulfide ores such as those commonly used to obtain copper, zinc, or lead, are roasted before smelting in order to convert the sulfides to oxides, which are more readily reduced to the metal. Roasting heats the ore in the presence of oxygen from air, oxidizing the ore and liberating the sulfur as sulfur dioxide gas.

The history of glass-making dates back to at least 3,600 years ago in Mesopotamia. However, most writers claim that they may have been producing copies of glass objects from Egypt. Other archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or Egypt. The earliest known glass objects, of the mid 2,000 BCE, were beads, perhaps initially created as the accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Glass products remained a luxury until the disasters that overtook the late Bronze Age civilizations seemingly brought glass-making to a halt.

Development of glass technology in India may have begun in 1,730 BCE.

Mineral wool is any fibrous material formed by spinning or drawing molten mineral or rock materials such as slag and ceramics. It was first manufactured in the 19th century. Applications include thermal insulation (as both structural insulation and pipe insulation), filtration, soundproofing, and hydroponic growth medium. Mineral wool can cause irritation to the eyes, skin and lungs, especially during its manufacture and installation.

A bloomery is a type of metallurgical furnace once used widely for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called a bloom. The mix of slag and iron in the bloom, termed sponge iron, is usually consolidated and further forged into wrought iron. Blast furnaces, which produce pig iron, have largely superseded bloomeries.

Dross is a mass of solid impurities floating on a molten metal or dispersed in the metal, such as in wrought iron. It forms on the surface of low-melting-point metals such as tin, lead, zinc or aluminium or alloys by oxidation of the metal. For higher melting point metals and alloys such as steel and silver, oxidized impurities melt and float making them easy to pour off.

With wrought iron, hammering and later rolling remove some dross.With tin and lead the dross can be removed by adding sodium hydroxide pellets, which dissolve the oxides and form a slag. If floating, dross can also be skimmed off.

In metallurgy, a flux is a chemical reducing agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time. They are used in both extractive metallurgy and metal joining. They are named for the ability to make molten metals easier to flow during smelting.

Some of the earliest known fluxes were sodium carbonate, potash, charcoal, coke, borax, lime, lead sulfide and certain minerals containing phosphorus. Iron ore was also used as a flux in the smelting of copper. These agents served various functions, the simplest being a reducing agent, which prevented oxides from forming on the surface of the molten metal, while others absorbed impurities into slag, which could be scraped off molten metal.

Swarf, also known as chips or by other process-specific names (such as turnings, filings, or shavings), are pieces of metal, wood, or plastic that are the debris or waste resulting from machining, woodworking, or similar subtractive (material-removing) manufacturing processes. Swarf can be small particles (such as the gritty swarf from grinding metal or the sawdust from sawing or sanding wood); long, stringy tendrils (such as the springy chips from turning tough metals, or long shavings from whittling); slag-like waste (such as is produced within pipe during pipefitting work); or stone fragments and dust (as in masonry).

Some of these terms are mass nouns (such as swarf and sawdust) and some of them are count nouns (such as chips, filings, or shavings).

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being supplied above atmospheric pressure.

In a blast furnace, fuel (coke), ores, and flux (limestone) are continuously supplied through the top of the furnace, while a hot blast of (sometimes oxygen-enriched) air is blown into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place throughout the furnace as the material falls downward. The end products are usually molten metal and slag phases tapped from the bottom, and flue gases exiting from the top. The downward flow of the ore along with the flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process.

Track ballast is the material which forms the trackbed upon which railroad ties (UK: sleepers) are laid. The term "ballast" comes from a nautical term for the stones used to stabilize a ship. Track ballast is packed between, below, and around the ties to bear the compression load of the railroad ties, rails, and rolling stock; to stabilize and restrain lateral movement of the track; to facilitate drainage; and keep down vegetation that can compromise the integrity of the combined track structure. Ballast also physically holds the track in place as the trains roll over it. Not all types of railway tracks use ballast.

A variety of materials have been used as track ballast, including crushed stone, washed gravel, bank run (unwashed) gravel, torpedo gravel (a mixture of coarse sand and small gravel), slag, chats, coal cinders, sand, and burnt clay.

Fundición Caletones or simply Caletones is a copper smelter plant in the Andes of Central Chile in Chile's O'Higgins Region in the Machalí commune. The smelter is integrated with the nearby copper mine of El Teniente, and both are owned by Codelco. After a failed attempt in the 1960s to expand the capacity using Peirce Smith converters (PSC) Caletones developed its own smelting technology becoming the birthplace of the Teniente Converter (TC), the first of which began operations in 1977.

At present Caletones has the capacity to each year process 1360 to 1400 kTon of concentrates and to produce 400 to 435 kTon cathode copper. As of 2015 it ranked second in Chile and among the 20 largest copper smelters in the world in terms of production capacity.

El Teniente (Spanish for "The Lieutenant") is the world's largest underground copper mine, located in the Andes Mountains of central Chile at an elevation of 2,300 metres (7,500 ft) above sea level. It is operated by the state-owned mining company Codelco and constitutes the largest division of its operations. Mining at the site dates back to at least 1819, but large-scale industrial extraction began in 1906 under U.S. ownership, initially through the Braden Copper Company and later Kennecott Copper Corporation. In 1971, during the presidency of Salvador Allende, Chile nationalized its copper industry and acquired full ownership of El Teniente. The mine contains more than 3,000 kilometres (1,900 mi) of tunnels and employs about five thousand workers. It was the site of the 1945 Smoke Tragedy, the deadliest metal mining accident in Chilean and world history. Since 2011, El Teniente has been undergoing a major expansion known as the New Mine Level project, which aims to extend operations deeper into the mountain without halting production. As of 2023 it is the third most productive copper mine in Chile after Los Pelambres and Escondida.

Converting is a type of metallurgical smelting that includes several processes; the most commercially important form is the treatment of molten metal sulfides to produce crude metal and slag, as in the case of copper and nickel converting. A now-uncommon form is batch treatment of pig iron to produce steel by the Bessemer process. The vessel used was called the Bessemer converter. Modern steel mills use basic oxygen process converters.

A spoil tip (also called a boney pile, culm bank, gob pile, waste tip or bing) is a pile built of accumulated spoil – waste material removed during mining. Spoil tips are not formed of slag, but in some areas, such as England and Wales, they are referred to as slag heaps and sometimes as pit heaps. In Scotland the word bing is used. In North American English the term is mine dump or mine waste dump.

The term "spoil" is also used to refer to material removed when digging a foundation, tunnel, or other large excavation. Such material may be ordinary soil and rocks (after separation of coal from waste), or may be heavily contaminated with chemical waste, determining how it may be disposed of. Clean spoil may be used for land reclamation.

A trickling filter is a type of wastewater treatment system. It consists of a fixed bed of some material, such as rocks, coke, gravel, slag, polyurethane foam, sphagnum peat moss, ceramic, or plastic media, over which sewage or other wastewater flows downward and causes a layer of microbial slime (biofilm) to grow, covering the bed of media. Aerobic conditions are maintained by splashing, diffusion, and either by forced-air flowing through the bed or natural convection of air if the filter medium is porous. The treatment of sewage or other wastewater with trickling filters is among the oldest and most well characterized treatment technologies.

The fundamental components of a complete trickling filter system are: