Methods of melting ice using ice-melt compositions including calcium chloride coated with a lignosulfonate material are disclosed. The ice-melt compositions can be useful as ice-melt products with improved safety. A method can include applying an ice-melt composition to ice, the ice-melt composition comprising coated particles. Each coated particle can include a core comprising calcium chloride and a coating at least partially surrounding the core, the coating comprising a lignosulfonate material.

Provided herein are methods comprising a) calcining limestone in a cement plant to form carbon dioxide and calcium compound selected from calcium oxide, calcium hydroxide, or combination thereof; b) treating the calcium compound with N-containing salt in water to produce an aqueous solution comprising calcium salt and N-containing salt; and c) contacting the aqueous solution with the carbon dioxide under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant aqueous solution wherein the calcium carbonate comprises vaterite.

A process for the isolation and purification of substantially pure chemicals, including silica gel, sodium silicate, aluminum silicate, iron oxide, and rare earth elements (or rare earth metals, REEs), from massive industrial waste coal ash including a plurality of caustic extractions of coal ash at an elevated temperature, followed by an acidic treatment to dissolve aluminum silicate and REEs. Dissolved aluminum silicate is precipitated out by pH adjustment as a solid product while REEs remain in the solution. REEs are captured and enriched using an ion exchange column. Alternatively, the solution containing aluminum silicate and REEs is heated to produce silica gel, which is separated from the enriched REEs solution. REEs are then isolated and purified from the enriched solution to afford substantially pure individual REE by a ligand-assisted chromatography.

A process for the isolation and purification of substantially pure chemicals, including silica gel, sodium silicate, aluminum silicate, iron oxide, and rare earth elements (or rare earth metals, REEs), from massive industrial waste coal ash including a plurality of caustic extractions of coal ash at an elevated temperature, followed by an acidic treatment to dissolve aluminum silicate and REEs. Dissolved aluminum silicate is precipitated out by pH adjustment as a solid product while REEs remain in the solution. REEs are captured and enriched using an ion exchange column. Alternatively, the solution containing aluminum silicate and REEs is heated to produce silica gel, which is separated from the enriched REEs solution. REEs are then isolated and purified from the enriched solution to afford substantially pure individual REE by a ligand-assisted chromatography.

An analytical method for precipitated particles using a co-precipitation reaction in includes feeding streams and a tracking metal into a reaction vessel; collecting a precipitated product containing the tracking metal from the reaction vessel in increments of time to obtain product samples; filtering each collected product sample to separate precipitated particles from filtrate; and performing elemental analysis for the tracking metal in the precipitated particles of each collected product sample and measuring a concentration of the tracking metal in the precipitated particles, to obtain a residence time distribution of the precipitated particles in the reaction vessel according to the concentration of the tracking metal in the precipitated particles. Therefore the preferred residence time of the precipitated particles in the reaction vessel can be ascertained, so that it is clear when the precipitated particles should be collected from the reaction vessel.

An analytical method for precipitated particles using a co-precipitation reaction in includes feeding streams and a tracking metal into a reaction vessel; collecting a precipitated product containing the tracking metal from the reaction vessel in increments of time to obtain product samples; filtering each collected product sample to separate precipitated particles from filtrate; and performing elemental analysis for the tracking metal in the precipitated particles of each collected product sample and measuring a concentration of the tracking metal in the precipitated particles, to obtain a residence time distribution of the precipitated particles in the reaction vessel according to the concentration of the tracking metal in the precipitated particles. Therefore the preferred residence time of the precipitated particles in the reaction vessel can be ascertained, so that it is clear when the precipitated particles should be collected from the reaction vessel.

A method of improving rheological properties of a divalent brine based downhole treatment fluid at an elevated temperature comprises adding to the divalent brine based downhole treatment fluid a rheological modifier, which comprises a carboxylic acid ester, or a phosphate ester blended with an ethoxylated glycol, or a combination comprising at least one of the foregoing in an amount effective to improve the rheological properties of the divalent brine based downhole treatment fluid at a temperature of greater than about 200 F. The divalent brine based downhole treatment fluid comprises calcium bromide, calcium chloride, zinc bromide, zinc chloride, or a combination comprising at least one of the foregoing.

A method for recovery of salts comprises providing (210) of an initial aqueous solution comprising ions of Na, K, Cl and optionally Ca or a material which when brought in contact with water forms an initial aqueous solution comprising ions of Na, K, Cl and optionally Ca. The start material is treated (230) into an enriched aqueous solution having a concentration of CaCl.sub.2 of at least 15% by weight. The treatment (230) comprises at least one of reduction of water content and addition of Ca. The treatment (230) generates a solid mix of Na Cl and KCl. The solid mix of NaCl and KCl is separated (235) from the enriched aqueous solution, giving a depleted aqueous solution comprising ions of Ca and Cl as main dissolved substances. An arrangement for recovery of salts is also disclosed.

Ice-melt compositions including calcium chloride coated with a lignosulfonate material are disclosed. The ice-melt compositions can be useful as ice-melt products with improved safety. Also disclosed are methods of melting ice using an ice-melt composition and methods of making an ice-melt composition.

Ice-melt compositions including calcium chloride coated with a lignosulfonate material are disclosed. The ice-melt compositions can be useful as ice-melt products with improved safety. Also disclosed are methods of melting ice using an ice-melt composition and methods of making an ice-melt composition.