US 2016/0176711 A1Published application

Process for purification of hydrofluoric acid including obtaining arsenious acid by-product

AssigneeMexichem Fluor, Sociedad Anonima de Capital Variable

InventorsIris Samantha DURÁN CASTILLO, Juan Alberto JUÁREZ GARCÍA, Nilo MARTÍNEZ ROBLES

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Abstract

The process for purification of hydrofluoric acid as herein disclosed is able to reduce the content of heavy metals, including arsenic, to values lower than 5 ppm without using any chemicals and with an integrated design of hot and cold streams that provide low energy consumption. Likewise, it achieves the extraction of heavy metals, especially arsenic, with minimal waste generation and maintaining its original oxidation state, which for the case of arsenic is +3, so that the residue can be converted into a product with commercial value, that in this process is obtained as arsenious acid. The process consists of four systems: HF purification system, arsenic concentration system, hot water system, and cold water system. This document discloses the synchronized operation of these 4 systems that together achieve what is mentioned in the previous paragraph.

Claims15

Dependent claims

Process for purifying hydrofluoric acid including obtaining arsenious acid (H3AsO3) byproduct, comprising the steps of:

A. PURIFICATION HF (REMOVAL AsF3)
a1. Feeding high-arsenic HF to the purifying column
a2. Evaporating HF at the bottom of the purifying column.
a3. Condensing the HF that leaves the dome of the purifying column.
a4. Returning liquid HF to the purifying column.
a5. Purging the bottom of the purifying column.
B. CONCENTRATION OF AsF3
b6. Feeding high-AsF3 HF (20,000 to 60,000 ppm) to the concentrator column.
b7. Evaporating high-AsF3 HF at the bottom of the concentrator column.
b8. Condensing the HF gas leaving the dome of the concentrator column.
b9. Returning liquid HF to the concentrator column.
b10. Purging the bottom of the concentrator column.
C. HYDROLYSIS OF ASF3
c11. Storing the AsF3
c12. Hydrolyzing AsF3 purge by reaction with water,
wherein the columns work by an energy integration system consisting of two circuits:
ice water circuit and hot water circuit.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/640,387Filed 6 Mar 2015
Priority: MX MX/A/2014/01588518 Dec 2014
Published: 23 Jun 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

C01B 7/196
Separation; Purification: by distillation
B01D 3/007
Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping: energy recuperation; Heat pumps
B01D 3/143
Fractional distillation or use of a fractionation or rectification column: by two or more of a fractionation, separation or rectification step
C01G 28/005
Compounds of arsenic: oxides; Hydroxides; Oxyacids