What happens when borax is heated with calcium oxide?

Answer 1

oxidized the arsenic into the highly toxic and volatile arsenic oxide, adding to the notoriety of the ore.Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt circa 1735, showing it to be a previously unknown element, distinct from bismuth and other traditional metals. Brandt called it a new "semi-metal". He showed that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt. Cobalt became the first metal to be discovered since the pre-historical period. All other known metals (iron, copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no recorded discoverers.During the 19th century, a significant part of the world's production of cobalt blue (a dye made with cobalt compounds and alumina) and smalt (cobalt glass powdered for use for pigment purposes in ceramics and painting) was carried out at the Norwegian Blaafarveværket. The first mines for the production of smalt in the 16th century were located in Norway, Sweden, Saxony and Hungary. With the discovery of cobalt ore in New Caledonia in 1864, the mining of cobalt in Europe declined. With the discovery of ore deposits in Ontario, Canada in 1904 and the discovery of even larger deposits in the Katanga Province in the Congo in 1914, the mining operations shifted again. When the Shaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production. The impact on the world cobalt economy from this conflict was smaller than expected: cobalt is a rare metal, the pigment is highly toxic, and the industry had already established effective ways for recycling cobalt materials. In some cases, industry was able to change to cobalt-free alternatives.In 1938, John Livingood and Glenn T. Seaborg discovered the radioisotope cobalt-60. This isotope was famously used at Columbia University in the 1950s to establish parity violation in radioactive beta decay.After World War II, the US wanted to guarantee the supply of cobalt ore for military uses (as the Germans had been doing) and prospected for cobalt within the U.S. border. An adequate supply of the ore was found in Idaho near Blackbird canyon in the side of a mountain. The firm Calera Mining Company started production at the site.It has been argued that cobalt will be one of the main objects of geopolitical competition in a world running on renewable energy and dependent on batteries, but this perspective has also been criticised for underestimating the power of economic incentives for expanded production. The stable form of cobalt is produced in supernovae through the r-process. It comprises 0.0029% of the Earth's crust. Free cobalt (the native metal) is not found on Earth because of the oxygen in the atmosphere and the chlorine in the ocean. Both are abundant enough in the upper layers of the Earth's crust to prevent native metal cobalt from forming. Except as recently delivered in meteoric iron, pure cobalt in native metal form is unknown on Earth. The element has a medium abundance but natural compounds of cobalt are numerous and small amounts of cobalt compounds are found in most rocks, soils, plants, and animals.In nature, cobalt is frequently associated with nickel. Both are characteristic components of meteoric iron, though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric iron alloys may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal, though neither element is seen in that form in the ancient terrestrial crust.Cobalt in compound form occurs in copper and nickel minerals. It is the major metallic component that combines with sulfur and arsenic in the sulfidic cobaltite (CoAsS), safflorite (CoAs2), glaucodot ((Co,Fe)AsS), and skutterudite (CoAs3) minerals. The mineral cattierite is similar to pyrite and occurs together with vaesite in the copper deposits of Katanga Province. When it reaches the atmosphere, weathering occurs; the sulfide minerals oxidize and form pink erythrite ("cobalt glance": Co3(AsO4)2·8H2O) and spherocobaltite (CoCO3).Cobalt is also a constituent of tobacco smoke. The tobacco plant readily absorbs and accumulates heavy metals like cobalt from the surrounding soil in its leaves. These are subsequently inhaled during tobacco smoking. Cobalt is a trace metal involved in photosynthesis and nitrogen fixation detected in most ocean basins and is a limiting micronutrient for phytoplankton and cyanobacteria. The Co-containing complex cobalamin is only synthesized by cyanobacteria and a few archaea, so dissolved cobalt concentrations are low in the upper ocean. Like Mn and Fe, Co has a hybrid profile of biological uptake by phytoplankton via photosynthesis in the upper ocean and scavenging in the deep ocean, although most scavenging is limited by complex organic ligands. Co is recycled in the ocean by decaying organic matter that sinks below the upper ocean, although most is scavenged by oxidizing bacteria.Sources of cobalt for many ocean bodies include rivers and terrestrial runoff with some input from hydrothermal vents. In the deep ocean, cobalt sources are found lying on top of seamounts (which can be large or small) where ocean currents sweep the ocean floor to clear sediment over the span of millions of years allowing them to form as ferromanganese crusts. Although limited mapping of the seafloor has been done, preliminary investigation indicates that there is a large amount of these cobalt-rich crusts located in the Clarion Clipperton Zone, an area garnering increasing interest for deep sea mining ventures due to the mineral-rich environment within its domain. Anthropogenic input contributes as a non-natural source but in very low amounts. Dissolved cobalt (dCo) concentrations across oceans are controlled primarily by reservoirs where dissolved oxygen concentrations are low. The complex biochemical cycling of cobalt in the ocean is still somewhat misunderstood, but patterns of higher concentrations have been found in areas of low oxygen such as the Oxygen Minimum Zone (OMZ) in the Southern Atlantic Ocean.Cobalt is considered toxic for marine environments at high concentrations. Safe concentrations fall around 18 μg/l in marine waters for plankton such as diatoms. Most coastal toxicity levels are influenced by anthropogenic input like sewage runoff and burning of fossil fuels. High levels of Co and Se have been recorded in seafood sourced from coastal areas with higher levels of the trace metals. Although scientists are aware of threatening toxicity, less attention has been paid compared to other trace metals like mercury and lead in contaminated water systems. The main ores of cobalt are cobaltite, erythrite, glaucodot and skutterudite (see above), but most cobalt is obtained by reducing the cobalt by-products of nickel and copper mining and smelting.Since cobalt is generally produced as a by-product, the supply of cobalt depends to a great extent on the economic feasibility of copper and nickel mining in a given market. Demand for cobalt was projected to grow 6% in 2017.Several methods exist to separate cobalt from copper and nickel, depending on the concentration of cobalt and the exact composition of the used ore. One method is froth flotation, in which surfactants bind to ore components, leading to an enrichment of cobalt ores. Subsequent roasting converts the ores to cobalt sulfate, and the copper and the iron are oxidized to the oxide. Leaching with water extracts the sulfate together with the arsenates. The residues are further leached with sulfuric acid, yielding a solution of copper sulfate