Abstract: Fresh water contamination by heavy metals results from a variety of sources and can be damaging to wildlife, alter landscapes, and impact human health. metals removal form water sources is desirable for improving water quality and preventing adverse effects, but also for metals collection and recycling. Adsorption is a desirable metals extraction technique due to economic feasibility. Nanoscale materials exhibit high surface-area-to-volume ratio that lends to high adsorption and reactivity, making them ideal candidates for adsorptive metals extraction processes. Despite these properties, nanomaterials have elicited safety concerns. The extraordinarily small dimensions of these materials allow them to maneuver biological systems, tissues, and even cells, and combined with high reactivity, this translocation can result in toxic effects. It is therefore imperative that safety of nanomaterials for metals extraction be evaluated in addition to adsorptive properties.

Abstract: Silicon-containing products, such as silicon, silicon carbide and silicon nitride, containing less than 0.01 weight percent total mineral impurities and selectively determined carbon-to-silicon ratios. The products are derived from plant matter, such as rice hulls and rice straw, containing at least three weight percent silica. Methods are provided for making such high purity silicon-containing products by leaching silica-containing plant matter with aqueous sulfuric acid under controlled temperatures, pressures and reaction times to remove minerals and metals while adjusting the mole ratio of fixed carbon to silica, and then thermally treating under controlled conditions to produce the desired product.

Abstract: Silicon-containing products, such as silicon, silicon carbide and silicon nitride, containing less than 0.01 weight percent total mineral impurities and selectively determined carbon-to-silicon ratios. The products are derived from plant matter, such as rice hulls and rice straw, containing at least three weight percent silica. Methods are provided for making such high purity silicon-containing products by leaching silica-containing plant matter with aqueous sulfuric acid under controlled temperatures, pressures and reaction times to remove minerals and metals while adjusting the mole ratio of fixed carbon to silica, and then thermally treating under controlled conditions to produce the desired product.

Abstract: A method for the production of fine-grain tungsten carbide (WC) powder comprising heating a tungsten precursor compound in contact with a gas mixture including a hydrocarbon such as methane (CH4). The method is preferably a one-step continuous method wherein the heating rate and reaction temperature is well controlled for the economical production of high quality tungsten carbide powder. The tungsten carbide powder advantageously has a high purity and a small crystallite size and can be used in the manufacture of products such as cutting tools having high wear resistance.

Abstract: A copper alloy plumbing fixture containing interdispersed lead particles coated non-continuously on a water contact surface to resist the leaching of lead into potable water systems. The leach resistant fixture is prepared by immersing conventional copper alloys in a bismuth nitrate solution, selectively and non-continuously coating the lead dispersoid particles on the water contact surface with bismuth, tin or copper.

Abstract: A method for treating a brass fixture having a fluid-contacting surface with lead dispersoids exposed thereon to reduce lead leaching into a fluid supply by contacting the brass fixture with a liquid metal solution selected from the group consisting of a liquid sodium solution, a liquid potassium solution and a liquid metal alloy solution to dissolve lead dispersoids from the fixture, wherein the metal alloy comprises a metal selected from the group consisting of sodium and potassium.

Abstract: A process for forming a salt, such as sodium tungstate, using a pyrometallurgical operation is provided. A slagging operation is performed in which a metal-containing material is melted in the presence of slag formers such as sodium metasilicate and silica. The metal predominantly reports to a denser metal-containing phase. The denser metal-containing phase may then be subjected to gas sparging with a carbon-containing gas in order to form metal carbide, preferably tungsten carbide.

Abstract: The present invention is a method to remove arsenic from arsenic-containing materials, such as an ore or concentrate, by roasting the arsenic-containing material to convert arsenic sulfides into arsenic oxides. The arsenic oxides are contained in the roasted arsenic-containing material. The roasted arsenic-containing material is contacted with a lixiviant to solubilize the arsenic in the oxide in a pregnant leach solution. Ferric arsenate, an environmentally stable compound, is formed in the lixiviant. The ferric arsenate can be removed to provide a treated solution complying with environmental regulations. The method provides a simple and effective technique for removing arsenic from arsenic-containing materials.

Abstract: A copper alloy plumbing fixture containing interdispersed lead particles coated noncontinuously on a water contact surface to resist the leaching of lead into potable water systems. The leach resistant fixture is prepared by immersing conventional copper alloys in a bismuth nitrate solution, selectively and noncontinuously coating the lead dispersoid particles on the water contact surface with bismuth. Tin may be substituted for bismuth to obtain similar results.

Abstract: A copper alloy plumbing fixture containing interdispersed lead particles coated noncontinuously on a water contact surface to resist the leaching of lead into potable water systems. The leach resistant fixture is prepared by immersing conventional copper alloys in a bismuth nitrate solution, selectively and noncontinuously coating the lead dispersoid particles on the water contact surface with bismuth. Tin may be substituted for bismuth to obtain similar results.

Abstract: A process for treating brass plumbing components to reduce leachable lead when the component is subsequently exposed to water includes exposing the brass component in an aqueous solution containing a desired concentration of chloride and pyrophosphate, with the chloride ion promoting the dissolution of lead from the brass component and the pyrophosphate ion preventing saturation of the solution with lead insuring continuation of the dissolution process.

Abstract: A sequential flotation process for the recovery of high-grade concentrates of copper, lead and cobalt-nickel from sulfide ores is provided. A primary grind ore pulp is conditioned with SO.sub.2 as H.sub.2 SO.sub.3 under intense aeration, and the conditioned pulp subjected to sequential flotation, with regrinding and conditioning of a copper rougher concentrate obtained in the first flotation step for copper.