WO2017003311A1

WO2017003311A1 - A method of recovering iron compounds contained in the sediments from drinking water treatment process and obtaining the inorganic concentrate with high iron content

Info

Publication number: WO2017003311A1
Application number: PCT/PL2016/000068
Authority: WO
Inventors: Roman PRZYTARSKI
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-29
Filing date: 2016-06-29
Publication date: 2017-01-05
Anticipated expiration: 2017-12-29
Also published as: PL412906A1

Abstract

The subject of the invention is a method of recovering iron compounds contained in the sediments produced in the process of drinking water treatment (in sediment from water clarification), the iron removal and obtaining inorganic concentrate with particularly high iron content, suitable for further industrial use. The invention allows the recovery of iron compounds contained in the deposit from the sedimentation during treatment (clarification) of water, in particular drinking water, including the iron removal, comprising taking the sediment out of the settling tank, drying by providing the surplus of water outflow and then applying sintering in 400 to 800 degrees Celsius, in special cases up to 1800 degrees Celsius, for a certain time, so there is created the concentrate with a high iron content, in the form of granules.

Description

A method of recovering iron compounds contained in the sediments from drinking water treatment process and obtaining the inorganic concentrate with high iron content

The subject of the invention is a method of recovering iron compounds contained in the sediment produced in the process of drinking water treatment (in sediment from water clarification), the iron removal and obtaining inorganic concentrate with particularly high iron content, suitable for further industrial use.

The result of commonly used water treatment processes, including the iron removal, after draining the clarified water, is sedimentation of the sludge originating from the precipitation of organic compounds, and therein included particles of iron, or filtering water with iron contained in the form of a colloid. The resulting sediment in settling tanks, and their weight is estimated at 2 to 5% by weight of mass of purified water, are removed for storing up in free-space in the form of heaps. These deposits contain significant amounts of iron compounds.

Applied rules of storage of the sediment from water clarification cause the iron in these deposits is actually lost and, together with the whole sediment, is a waste, classified according to the catalog of wastes established by the Regulation of Minister of the Environment of the Republic of Poland from the 27th September 2001 as a waste no 19.09.02. Moreover, these deposits stored in landfills pose an ecological threat due to a slight biodegradability and the possibility of a slow but systematic release of chemicals from the landfill to the environment. This applies among others to metal ions including iron ions. Currently there is not any larger scale action taken to eliminate these phenomena, and there is not known any way to eliminate them. The aim of the invention is to enable the recovery of iron compounds to use iron in the material recycling, as well as reducing environmental damage.

The basis of the invention is the use of a procedure of eliminating the majority of organic elements from the sediment, leaving the inorganic elements, in particular iron.

A method of recovering iron compounds contained in the sediments resulting from sedimentation in drinking water treatment processes (in sediments from water clarification), including the process of iron removal, lies on the fact that the sediment after taking out from the settling tank and drying, especially gravitative, is subjected to sinter in high temperature, preferably in a blast furnace in the temperature ranging from 400 to 800 degrees Celsius (in special cases up to 1800 degrees Celsius) with the air flow and movement of sediments during sintering, preferably for a period of 20 to 60 minutes, depending on the properties of the sediment. A surprising effect of this process is production of a substantially inorganic concentrate, with substantial and predominant iron content in relation to other components, in the form of granules. This granulate can be used as a feedstock for meailurgicai manufacture of metallic iron and its alloys, or processed in the form of powder or granules can be used as a sorbent, a filler / pigment for building ceramics wares.

Example: In a typical water treatment station applying a treatment process using flocculants, sludge from the settling tank, after reaching the sedimentation condition, has been taken out and piaced on the ground covered with concrete, in the shape of a prism with a height of approximately 2 meters. The sedimentary prism has been shielded under a permanent shelter and left for a period of approximately 2 months. Thus the precipitate, pre-dried under its own weight, was next inserted as a batch into the rotary kiln retaining the temperature up to 800 degrees Celsius inside the chamber. Consecutive batches of precipitate were moving in a rotating oven remaining in the sintering zone between 20 and 60 minutes.

The granular material was created after completion of the sintering process, with homogeneous morphology, an irregular size, usually having a diameter of 1 to 3 mm. It was removed from the furnace to be cooled and transferred to the container.

Samples of this material were examined under electron microscope SEM / EDS, in the laboratory of instrumental analyses of the Department of Chemistry at the University of Nicolaus Copernicus. The results of the study from 16 February 2015 are presented on the Fig. 1 reading. The resulting elemental composition was as follow: coal - 5% by weight, oxygen - 32% by weight, magnesium - 1% by weight, aluminum - 3% by weight, silicon - 7% by weight, phosphorus - 2% by weight, calcium - 5% by weight, manganese - 1 % by weight, iron - 43% by weight, other - 1% by weight.

The process was repeated, there has been reached a considerable convergence of the results and the detected iron content was suitable for industrial use in accordance with the description of the invention, with the possibility of processing for customization.

A number of attempts of sintering in higher temperatures, up to 1800 degrees Celsius, were carried out achieving the desired effect.

Claims

Patent ciaim

1. A method of recovering iron compounds contained in the sediments produced in the process of drinking water treatment, including the iron removal, and obtaining inorganic concentrate with a high iron content The method is comprising recurring taking out a batch of sediment from the settling tank and drying, characteristic in fact that the deposit so prepared is subjected to sintering, preferably in a blast furnace in the temperature between 400 to 800 degrees Celsius, in special cases up to 1800 degrees Celsius, with air flow and movement of the deposit during the sintering in the period from 20 to 60 minutes, depending on the properties of the sediment.