A method for treating a purge stream derived from a sodium carbonate, sesquicarbonate, wegsheiderite, or bicarbonate crystallizer, said purge stream comprising sodium carbonate and/or sodium bicarbonate and at least 1% by weight of sodium chloride and/or sodium sulfate, the method comprising: causticizing at least 50 mol. % of the sodium from sodium carbonate and/or sodium bicarbonate into a caustic solution and into a calcium carbonate mud with lime and water, separating the calcium carbonate mud from the caustic solution; concentrating the caustic solution by removing part of the water to obtain a concentrated caustic solution comprising at least 25% NaOH, and a crystallized solid comprising sodium carbonate and sodium chloride and/or sulfate, separating the crystallized solid from the concentrated caustic solution, said crystallized solid to be disposed of or to be further valorized, recycling part of the concentrated caustic solution to the sodium carbonate, sesquicarbonate, wegsheiderite, or bicarbonate crystallizer.

A process for recovering alkali from power boiler ash is provided. The power boiler ash is first contacted with Na.sub.2CO.sub.3 to produce a mixture containing settling and non-settling solid particles. A fraction of the settling particles is then separated from the mixture to produce a first clarified alkaline solution. The first clarified alkaline solution contains species such as NaOH and KOH depending upon the power boiler ash characteristics. The non-settling solid particles may optionally be further separated from the first clarified alkaline solution to obtain a second clarified alkaline solution. This process is also applicable for the extraction of alkali from other oxide/hydroxide containing materials.

A method for producing a concentrated aqueous sodium hydroxide solution from a purge stream deriving from a sodium carbonate, or sesqui-carbonate, or wegsheiderite crystallizer, or sodium bicarbonate crystallizer, said purge stream comprising sodium carbonate and/or bicarbonate, and at least 1% of sodium chloride or sodium sulfate and a soluble impurity from an ore deposit comprising at least one of the following elements: As, Ba, B, Ca, Co, K, Li, Mo, P, Pb, Se, Sn, Sr, Te, Tl, Ti, V, and W, to be purified, the method comprising: causticizing at least 50 mol. % of the sodium carbonate into a caustic solution and into a calcium carbonate mud with lime and water; separating the mud from the caustic solution; concentrating the caustic solution by removing part of the water to obtain a concentrated caustic solution comprising at least 25% NaOH, and a crystallized solid comprising sodium carbonate and sodium chloride and/or sulfate; and separating the crystallized solid from the concentrated caustic solution, said crystallized solid to be disposed of or to be further valorized.

A method for producing a concentrated aqueous sodium hydroxide solution from a purge stream deriving from a sodium carbonate, or sesqui-carbonate, or wegsheiderite crystallizer, or sodium bicarbonate crystallizer, said purge stream comprising sodium carbonate and/or bicarbonate, and at least 1% of sodium chloride or sodium sulfate and a soluble impurity from an ore deposit comprising at least one of the following elements: As, Ba, B, Ca, Co, K, Li, Mo, P, Pb, Se, Sn, Sr, Te, Tl, Ti, V, and W, to be purified, the method comprising: causticizing at least 50 mol. % of the sodium carbonate into a caustic solution and into a calcium carbonate mud with lime and water; separating the mud from the caustic solution; concentrating the caustic solution by removing part of the water to obtain a concentrated caustic solution comprising at least 25% NaOH, and a crystallized solid comprising sodium carbonate and sodium chloride and/or sulfate; and separating the crystallized solid from the concentrated caustic solution, said crystallized solid to be disposed of or to be further valorized.

The present invention provides an optimized method for recovering high-purity lithium carbonate from a lithium-containing composite oxide such as lithium silicate, lithium aluminum oxide, or lithium aluminum silicate deposited on an erosion surface of a discarded waste sagger. Therefore, when the method for producing high-purity lithium carbonate from a waste sagger of the present invention is used, it is expected not only to be able to produce high-purity lithium carbonate that can be used for manufacturing lithium secondary batteries by recycling a discarded waste sagger, but also to be able to recycle a positive electrode active material, iron oxide, alumina, silicate, calcium carbonate, and the like obtained as by-products during the production process of the lithium carbonate.

The subject process relates generally to producing an aqueous solution through a simple but highly effective chemical reaction. The aqueous solution is composed of a blended solution with water and an added solubilizer for the chemical reaction. The results produce an ionic solid and an alkaline liquid solution which are useful commercial products, and various applications including but not limited to use as a CO.sub.2 capture solvent.

The subject process relates generally to producing an aqueous solution through a simple but highly effective chemical reaction. The aqueous solution is composed of a blended solution with water and an added solubilizer for the chemical reaction. The results produce an ionic solid and an alkaline liquid solution which are useful commercial products, and various applications including but not limited to use as a CO.sub.2 capture solvent.

The present invention addresses to a method of removing scale from the DHSV of the oil production string aiming at maintaining the production of the wells and thus avoiding the loss of production. First, a neutralizing solution is placed in the service line, before pumping the scale removing solution through the string to act on the DHSV. Next, the acid is pumped into the production string to react with the calcium carbonate scale. After the time for the dissolution of the scale inside the DHSV, the well is opened for production by the service line. The spent acid is mixed with the neutralizing solution inside the service line, reducing its corrosiveness in relation to the service line, contributing to its preservation.

The present invention addresses to a method of removing scale from the DHSV of the oil production string aiming at maintaining the production of the wells and thus avoiding the loss of production. First, a neutralizing solution is placed in the service line, before pumping the scale removing solution through the string to act on the DHSV. Next, the acid is pumped into the production string to react with the calcium carbonate scale. After the time for the dissolution of the scale inside the DHSV, the well is opened for production by the service line. The spent acid is mixed with the neutralizing solution inside the service line, reducing its corrosiveness in relation to the service line, contributing to its preservation.