AngloGold Ashanti Brasil Mineracao is a leading producer of gold in the world. AngloGold was working on production plans for the Cuiaba Gold Mining Expansion Project located at Nova Lima, Minas Gerasis. The plant's production capacity is projected to be equivalent to 400 metric tons of sulfuric acid per day. The Promon Company worked on the design, procurement, construction and assembly services for the sulfuric acid plant that converts the sulfur oxide (SOx) produced as a byproduct of gold mining into sulfuric acid for sale in the marketplace, while also preventing its release as a gas into the atmosphere. AngloGold Ashanti sells sulfuric acid mainly to manufacturers of paper pulp, fertilizer and chemicals. AngloGold Ashanti's Cuiaba Expansion Project involved expansion of an existing unit with a goal for production of up to 6 tons of gold per year.
The facility has selected a wet electrostatic precipitator (WESP) engineered by Beltran Technologies, Inc.. of Brooklyn. NY, to clean the gas of impurities (mainly As. Hg, Cu, Fe, Zn, Cd, Pb, CI. Mn, Ti. Cr. S03, and sulfuric acid mist) before it enters the sulfuric acid plant. The Beltran WESPs offer several advantages ideally suited for the task of gas cleaning, especially the ability to efficiently capture and remove very fine sub-micron particulate and acid mist.
The corrosive nature of the flue gases demands special attention for the materials of construction of WESPs. The Beltran WESPs are fabricated using fiberglass reinforced plastic (FRP) and high nickel-chromium alloys. While historically many electrostatic precipitators used for acid mist applications have been constructed from lead. FRP precipitators are less expensive, easier to construct and maintain and are extremely corrosion resistant. The electrically conductive sections of the WESP are made from special conductive FRP. The system has achieved an overall efficiency of greater than 99 percent.
To prevent the formation of 'black' or contaminated acid and to protect the catalyst beds from fouling and plugging. Beltran WESPs are used to clean the off-gases before entry into the acid plant. The acid plants that must handle impure sulfur dioxide gas such as those emitted from metallurgical processes like ore roasters, flash smelters and spent acid regeneration, require the removal of acid mist, residual dust and fumes before the gases enter the drying tower.
Conventional scrubbing systems (wet or dry) are generally not effective in controlling sub-micron emissions, consisting primarily of acid gas mists, sub-micron particulates and condensed organics. Wet tubular electrostatic precipitators, because of their ability to generate multi-staged charging and strong electrical fields in a wet, cooled atmosphere, have been shown effective in cleaning the flue gas.
The Beltran WESPs use ionizing rods with star shaped discharge points in a square or hexagonal configuration. This unique geometry generates a corona field four to five times greater than other wet or dry ESPs. This enables Beltran WESPs to operate at up to 99.9 percent emission control efficiency on sub-micron particulates and acid mists, which was demonstrated at AmzloGold.
Wet operation virtually eliminates the re-entrainment problem of dry ESPs and other technologies. It also eliminates the need for mechanical or acoustic rappers for cleaning the collection plates. There is minimal impedance and pressure drop compared to scrubbers and other methods. This allows faster throughput, a simpler, smaller scale and less expensive components. The superior performance of Beltran WESPs has resulted in more efficient cleaning, greater efficiency, greater efficiency per energy use and lower total operating cost for AngloGold.
An array of complex air pollution issues places the metallurgical industry among the largest potential sources of pollutants, and one of the most tightly regulated industrial sectors. One fully integrated, nonferrous metal producer in India, however, is demonstrating that a company with a determined commitment to environmental protection, energy efficiency and sustainability can succeed in realizing those goals while remaining highly profitable -- provided it makes smart choices in emission control strategies and...
Gas cleaningNew and strict pollution regulations in metallurgical plants worldwide are restricting particulate and acid gas emissions to extremely low levels. Because of that, sulphuric acid plants are being installed to remove and utilise S02 in gases resulting from the roasting of sulphide ores, smelting of ores, and burning or regeneration of spent acid or acid sludge from petroleum refining. To prevent the formation of "black" or contaminated acid and to protect the catalyst beds from fouling and plugging,...
The technology is ready and, with state and federal tax credits waiting, the economics look better than ever: New Jersey, one of the first states to be industrialized, finds itself plagued with the contaminated aftermath of pre-EPA industries: soil contamination. From superfund sites to the gas station whose underground storage tank has been oozing for the last 20 years, every industry has contributed its bit. More and more sites are now ineligible for new construction because of prior contamination.
Government...
In our previous article about oil mist collector technology, we discussed the pros and cons of centrifugal mist collectors and filter-based mist collectors. Today, we look at the other two most common methods of getting oil mist out of the air.
Electrostatic Precipitator Mist Collectors An electrostatic precipitator uses high-voltage electricity to impart a positive charge onto the particles of mist carried by an air current. Then, the air is passed between a series of negatively-charged plates, and the positive...
Gas-phase air filtration is a highly specialized branch of air filtration with a very short list of reputable and knowledgeable companies manufacturing the dry-scrubbing media, filters, and systems in which they are employed. The list becomes even shorter when considering where to go for the technical resources necessary to specify, design, test, build, install, operate, and maintain the appropriate gas-phase air filtration media, filters, and systems for specific applications.
Purafil is asked every day by...
All fertilizer plants produce dust and gases, such as ammonia (NH3) and acid fumes, which must be removed at very high efficiencies before venting to atmosphere. Familiar examples are granulation and prilling of nitrogenous products such as Urea which is the most widely used fertilizer in the world(1). Phosphatic fertilizer production produces dust and Fluorine compounds. Typical air treatment unit operations at fertilizer plants are cooling, followed possibly by a venturi scrubber, then either wet or dry ESP and...
The CANSOLV® System scrubbing technology is the leading regenerable SO2 scrubbing process. It uses an aqueous amine solvent in a conventional amine treater process flowsheet configuration to achieve high-efficiency removal of SO2 from a large variety of gas streams. The technology is applicable to petroleum refining, natural gas sweetening, smelting of sulfide ores, power generation, pulp and paper plants and industrial boilers. Commercial plants are operating to treat sulfuric acid plant tail gas, prevent...
`In four years, half of San Diego may be filling its glasses with tap water that once ran through its toilets,` reported the San Diego Union-Tribune recently. A plan to mix `repurified water` with the City`s raw drinking water reservoir could become a reality, thanks to the wonders of water treatment technology.
Such a possibility elicits various reactions including disgust, marvel and fear. Although the public generally trusts and admires modern technology, politicians and even scientists fear the grave repercuss...
Of all the air pollution abatement technologies, wet scrubbing systems remain the most versatile and cost efficient. New, patented advances in venturi scrubbing of air particulate, aerosols and gases easily achieves removal efficiencies greater than 99% for particulate and aerosols less than 3 Fm. Sub-micron particles present a special concern because they cause (at the very least) irritation of the breathing passages and may, more importantly, include toxic and/or odorous compounds.
The use of membrane technology to produce water of greater and greater purity is rapidly evolving under the pressure of new product quality specifications, including those of the pharmaceutical and beverage industries. Membrane technology is well suited to achieving multi-component water specifications, given the fundamental nature of the separation process. Meeting a resistivity or conductivity specification as the sole gauge of water quality, however, can be more challenging. Membrane technology is capable of...
Introduction:
In this process, vacuum extraction is used to remove contaminants from soils. After condensation, contaminants are mixed with a semiconductor catalyst such (e.g., titanium dioxide), and fed through a reactor which is illuminated by sunlight. Ultraviolet light activates the catalyst, which results in the formation of reactive chemicals known as `radicals`. These radicals are powerful oxidizers that break down the contaminants into non-toxic by-products such as carbon dioxide and water.
A big...
Air Pollution Creates Acid Rain
Scientists have discovered that air pollution from the burning of fossil fuels is the major cause of acid rain. Acidic deposition, or acid rain as it is commonly known, occurs when emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx) react in the atmosphere with water, oxygen, and oxidants to form various acidic compounds. This mixture forms a mild solution of sulfuric acid and nitric acid. Sunlight increases the rate of most of these reactions.
These compounds then...
The textile industry is plagued by air pollution problems which must be resolved. In particular, smoke and odor arising in the process require abatement. Air pollution control technology is available today which will serve the textile industry well into the 21st century.
The nature of the problem
The major air pollution problem in the textile industry occurs during the finishing stages, where various processes are employed for coating the fabrics. Coating materials include lubricating oils, plasticizers,...
Introduction
Pollution Prevention Guidelines to provide technical advice and guidance to staff and consultants involved in pollution-related projects. The guidelines represent state-of-the-art thinking on how to reduce pollution missions from the production process. In many cases, the guidelines provide numerical targets for reducing pollution, as well as maximum emissions levels that are normally achievable through a combination of cleaner production and end-of-pipe treatment. The guidelines are designed to...
Introduction
Pollution Prevention Guidelines to provide technical advice and guidance to staff and consultants involved in pollution-related projects. The guidelines represent state-of-the-art thinking on how to reduce pollution emissions from the production process. In many cases, the guidelines provide numerical targets for reducing pollution, as well as maximum emissions levels that are normally achievable through a combination of cleaner production and end-of-pipe treatment. The guidelines are designed to...
Introduction
Pollution Prevention Guidelines to provide technical advice and guidance to staff and consultants involved in pollution-related projects. The guidelines represent state-of-the-art thinking on how to reduce pollution emissions from the production process. In many cases, the guidelines provide numerical targets for reducing pollution, as well as maximum emissions levels that are normally achievable through a combination of cleaner production and end-of-pipe treatment. The guidelines are designed to...
Introduction
Composting is a controlled biological process by which organic contaminants (e.g., PAHs) are converted by microorganisms (under aerobic and anaerobic conditions) to innocuous, stabilized byproducts. Typically, thermophilic conditions (54 to 65 °C) must be maintained to properly compost soil contaminated with hazardous organic contaminants. The increased temperatures result from heat produced by microorganisms during the degradation of the organic material in the waste. In most cases, this is...
Three technologies that are most commonly used to treat halogenated VOCs in air emissions/off-gases are carbon adsorption, catalytic oxidation, and thermal oxidation.
Carbon adsorption is a remediation technology in which pollutants are removed from air by physical adsorption onto the carbon grain. Carbon is `activated` for this purpose by processing the carbon to create porous particles with a large internal surface area (300 to 2,500 square meters per gram of carbon) that attracts and adsorbs organic molecules...
Introduction:
High temperatures, 870 to 1,200 °C (1,400 to 2,200 °F), are used to volatilize and combust (in the presence of oxygen) halogenated and other refractory organics in hazardous wastes. Often auxiliary fuels are employed to initiate and sustain combustion. The destruction and removal efficiency (DRE) for properly operated incinerators exceeds the 99.99% requirement for hazardous waste and can be operated to meet the 99.9999% requirement for PCBs and dioxins. Off gases and combustion residuals generally...
Common treatment technologies for halogenated SVOCs in soil, sediment, and sludge include biodegradation, dehalogenation, incineration, and excavation with off-site disposal.
All types of biodegradation, both in situ or ex situ, can be considered to remediate soils: in situ bioremediation, bioventing, composting, controlled solid phase, or landfarming. Slurry phase biological treatment is also applicable but is less widely used. Treatability studies should be conducted to evaluate design parameters, such as...
` Comparative risk assessment provides a systematic way to compare environmental problems that pose different types and degrees of health risk. It combines information on the inherent hazards of pollutants, exposure levels and population characteristics to predict the resulting health effects. Using data from available sources, rapid, inexpensive comparative risk assessments can identify the most significant health problems. Together with consideration of costs, technical feasibility and other factors, the...
Throughout American history, technological and institutional innovation has increased our prosperity. Public leadership has encouraged businesses, workers, and consumers to invest in new ideas that meet the challenges of one generation, paving the path to a better world for the next generation. The energy system that fuels our 20th century economy exemplifies such progress through partnership. Most of this system is built upon innovations of the 19th century, when coal was industrialized and oil commercialized,...
Introduction
Solidification/stabilization (S/S) reduces the mobility of hazardous substances and contaminants in the environment through both physical and chemical means. Unlike other remedial technologies, S/S seeks to trap or immobilize contaminants within their `host` medium (i.e., the soil, sand, and/or building materials that contain them), instead of removing them through chemical or physical treatment. Leachability testing is typically performed to measure the immobilization of contaminants. S/S techniques...
Introduction
The principle of electrokinetic remediation relies upon application of a low-intensity direct current through the soil between ceramic electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions, ammonium ions, and positively charged organic compounds move toward the cathode. Anions such as chloride, cyanide, fluoride, nitrate, and negatively charged organic compounds move toward the anode. The...
`The definition and selection of environmental performance indicators is still at an early stage but the use of indicators is increasing, both for the tracking of trends in pollution and other environmental issues at a large scale (national or regional) and also for the monitoring of Bank projects. This note provides a framework to assist in the selection of appropriate indicators for pollution projects, and discusses the issues that must be considered. It provides examples of some commonly used indicators of air...
Abstract This paper presents data on the source of PCDDs/PCDFs in cement plant stack emissions, demonstrating that these emissions are not necessarily all created by the process. The data potentially demonstrates that some of the PCDDs/PCDFs in the emissions are pre-existing dioxins and furans that are vaporized out of the kiln raw feed. This calls into question the assumption that PCDD/PCDF emissions can be decreased below a certain point. The EPA has acknowledged resuspended PCDD/PCDF emissions, such as from...
Electrostatic precipitation has been a reliable technology since the early 1900`s. Originally developed to abate serious smoke nuisances, the manufacturers of zinc, copper, and lead quickly found electric gas cleaning a cost efficient way to recover valuable product carried out of the stacks from furnace operations. Today electrostatic precipitators are found mainly on large power plants, cement plants, incinerators, and various boiler application.
In the wood products industry, the dry electrostatic precipitator...
Summary
Crossflow membrane filtration systems, such as reverse osmosis (RO), nanofiltration (NF) or ultrafiltration (UF), are good alternatives to traditional filtration and chemical treatment. However, to get the best performance from them, careful attention must be paid to feedwater conditions.
Pretreating feedwater can lengthen the life of membrane elements, improve the quality of the water produced and reduce the amount of maintenance and cleaning a system requires.
The importance of feedwater conditions...
There are several options in designing two-pass reverse osmosis systems, using the predominant membranes currently on the market: PA (polyamide) or CA (cellulose triacetate) membranes. Combining cellulose triacetate and polyamide membranes in the first and second passes, respectively, is just one approach that offers some interesting advantages, but it may not necessarily be suitable for all applications of two-pass reverse osmosis.
Using polyamide in both passes (PA/PA) provides a higher final product water and...
INTRODUCTION
If one were to select a single word describing the most important factor when applying membrane technology to a wastewater application, it would be chemistry. That is not to say that other factors are not important; certainly fluid dynamics and other physical science factors play a major role as well. But it is the chemistry that is so important to success.
And it is the chemistry that is so often overlooked.
All too often reverse osmosis, or any membrane system for that matter, is considered the...
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Beltran - Wet Electrostatic Precipitators