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Pollution Prevention and Control Technologies for Plating Operations

Section 3 - Chemical Recovery


3.3.5 Costs Capital Costs

The basic equipment costs and installed costs for vacuum evaporators are indicated in Exhibits 3-18 and 3-19 for heat generated (steam) and electric types. Equipment costs will vary depending on the materials of construction; costs shown are for the basic materials offered by the manufacturer. Evaporators are currently marketed with a wide range of construction materials to resist the corrosiveness of various plating chemicals. The more popular materials include titanium, tantalum, borosilicate glass, stainless steel and carbon steel. Most evaporators are supplied as package units and only require the hook-up of utilities before start-up. However, some ancillary equipment is required (e.g., tanks), which are reflected in the installed costs. The installed cost estimate (140% of basic equipment cost) is based on Users Survey data.

Due to the capital intensive nature of this technology, it is prudent that the buyer make every effort to reduce the flow rate of the feed stream by employing pollution prevention measures. Methods of flow reduction are discussed in Section 2.


Exhibits 3-18 & 3-19. Equipment Costs for Steam and Electric Type Vacuum Evaporators

When selecting a vacuum evaporator, the plater should consider, in addition to costs, the following: (1) availability, quantity and quality of steam, hot water or waste heat (i.e., if unavailable or insufficient, then choose one of the electric units); (2) cooling water requirements; (3) electrical power requirements; (4) maximum temperature that can be applied to the feed stream (i.e., concern for heat sensitive chemicals); (5) expected feed rate; (6) required solids concentration of product (i.e., how concentrated must the plating solution be before it can be returned to the bath); (7) anticipated use of distillate; (8) materials of construction (depends on both the type and maximum concentration of chemicals); (9) controls (most units have microprocessor controls for automatic operation and manual override); (10) auxiliary equipment requirements (e.g., bath maintenance technologies for removal of contaminants that will be returned to the bath by the evaporator); and (11) O & M requirements (level of expertise required and number of man-hours per year). Operating Costs

The primary operating costs for vacuum evaporators are labor, energy and cooling water. Energy and operating labor costs per gallon evaporated are shown in Exhibit 3-20. In this exhibit, a distinction is made between operating costs for segregated recovery and the concentration of mixed waste streams (e.g., end-of-pipe). Higher O&M costs can be expected for end-of-pipe applications because the solutions are evaporated to higher solids levels, which increases fouling and scaling.


Exhibit 3-20. Operating and Maintenance Costs for Vacuum Evaporators: Segregated Recovery (top) and Mixed Waste Concentration (bottom)

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