Bauxite residue recovery includes mixing a solution of hydrochloric acid (HCL) according to a predetermined concentration, and adding the HCL solution to a quantity of raw red mud recovered from industrial operations as waste material. The highly alkaline property of the bauxite residue, commonly known as red mud is at least partially neutralized from the HCL, and makes the resulting washed red mud more amenable to subsequent uses in various applications in fields such as construction, wastewater treatment, and metal recovery processes. The process recovers washed red mud from the red mud and HCL solution by filtering the raw red mud and HCL solution for generating a stream of leach liquor from the filtrate and the recovered washed red mud from the residue. The neutralized red mud is further treated to extract metals such as calcium, iron, aluminum, silicon, and titanium.

Porous amorphous silica can be obtained from siliceous plant matter containing non-siliceous inorganic substances. The siliceous plant matter is soaked in an aqueous solution which includes a chelating agent. The chelating agent is present in an amount which helps to extract at least some of the non-siliceous inorganic matter. The aqueous solution is then separated from the siliceous plant matter. Beneficial properties are imparted to the siliceous plant matter by controlling the amount of at least one preselected non-siliceous inorganic substance in the siliceous plant matter. At the end of the process, the siliceous plant matter is heat treated in the presence of oxygen at a temperature to produce the resulting amorphous silica having the beneficial properties.

The present invention describes an integrated process for carbon dioxide capture, sequestration and utilisation, which comprises: a) providing an aqueous slurry comprising an aqueous solution and a particulate solid comprising an activated magnesium silicate mineral; b) in a dissolution stage, contacting a CO.sub.2-containing gas stream with the aqueous slurry to dissolve magnesium from the mineral to provide a magnesium ion enriched aqueous solution and a magnesium depleted solid residue; c) recovering at least a portion of the magnesium depleted solid residue; d) in a separate acid treatment stage, reacting the recovered portion of the magnesium depleted solid residue with a solution comprising a mineral acid or acid salt to further dissolve magnesium and other metals and to provide an acid-treated solid residue; e) recovering the acid-treated solid residue; and f) in a separate precipitation stage, precipitating magnesium carbonate from the magnesium ion enriched aqueous solution.

Methods of synthesis of mesoporous silica are disclosed. The mesoporous silica synthesized herein, like SBA-15, possesses a two-dimensional, hexagonal, through-hole structure with a space group p6mm. An effective quantity of one or more water-soluble oxidized disulfide oil (ODSO) compounds are used during synthesis to impart distinct characteristics.

Methods of synthesis of mesoporous silica are disclosed. The mesoporous silica synthesized herein, like SBA-15, possesses a two-dimensional, hexagonal, through-hole structure with a space group p6mm. An effective quantity of one or more thermally expandable microcells are used during synthesis to impart distinct characteristics.

Porous amorphous silica can be obtained from siliceous plant matter containing non-siliceous inorganic substances. The siliceous plant matter is soaked in an aqueous solution which includes a chelating agent. The chelating agent is present in an amount which helps to extract at least some of the non-siliceous inorganic matter. The aqueous solution is then separated from the siliceous plant matter. Beneficial properties are imparted to the siliceous plant matter by controlling the amount of at least one preselected non-siliceous inorganic substance in the siliceous plant matter. At the end of the process, the siliceous plant matter is heat treated in the presence of oxygen at a temperature to produce the resulting amorphous silica having the beneficial properties.

Methods of synthesis of mesoporous silica are disclosed. The mesoporous silica synthesized herein, like SBA-15, possesses a two-dimensional, hexagonal, through-hole structure with a space group p6mm. An effective quantity of one or more water-soluble oxidized disulfide oil (ODSO) compounds are used during synthesis to impart distinct characteristics.

A process for recycling glass from screens deriving from the disposal of cathode-ray tube television sets with quantitative recovery of the lead in metal form, is described.

A process for preparing precipitated silica comprising a precipitation reaction between silicate and an acid, in which the acid used in at least one of the steps is a concentrated acid, preferably selected from the group consisting of sulfuric acid having a concentration of at least 80% by weight, in particular at least 90% by weight, acetic acid having a concentration of at least 90% by weight, formic acid having a concentration of at least 90% by weight, nitric acid having a concentration of at least 60% by weight, phosphoric acid having a concentration of at least 75% by weight, and hydrochloric acid having a concentration of at least 30% by weight.

The present invention provides an integrated process for carbon dioxide capture, sequestration and utilisation, which comprises: a) providing an aqueous slurry comprising an aqueous liquid and a particulate solid comprising an activated magnesium silicate mineral; b) in a dissolution stage, contacting a CO.sub.2-containing gas stream with the aqueous slurry at a first pressure to dissolve magnesium from the mineral to provide a slurry comprising a magnesium ion enriched carbonated aqueous liquid and a magnesium depleted solid residue; and c) in a precipitation stage, precipitating magnesium carbonate from magnesium ions dissolved in step b) by multiple successive stage-wise reductions in pressure, with each stage being at a lower pressure than the preceding stage;
wherein each successive stage-wise reduction in pressure releases CO.sub.2 which is correspondingly stage-wise compressed and recycled back into the dissolution stage.